Hmmm....you say you feel "unsafe"...this means that this person is as a person a dodgy character? I am still a little unsure if you have an issue with just another person on the premises (hence the valid logic of bills sharing etc) or whether you have an issue because this person makes you feel unsafe (which means there's something wrong with this particular human being)

Two things right? So for instance, if this person instead of being her bf had been her sister, and a nice and jolly girl, would you still object (leading me to believe that your real reason for objection is the another-person-on-the-premises-not-footing-bills issue)...

Once you can clearly think WHY you feel so strongly you can handle this better. :-)

I can't see that you have any reason to suspect that this guy is in any way 'dodgy'. As far as I can see he's only be reactive (and if you phrased the things to him as you have on here then I can sort of see why).
I don't see that you inviting complete strangers in (even if you're suggesting this in jest) is in any way equivalent to her bringing round her boyfriend. When you move in with someone you have to be sufficiently good friends with them to trust that the people they invite around will be decent people.
I'm afraid this strikes as a touch of immaturity (on both your fronts -- I don't think your friend has responded in the most compromising situation ever)....
I've had not dissimilar situations myself (actually -- probably worse, my flatmate at undergrad used to have sex with her door wide open, that I had to walk past to get to the bathroom!)... but with the benefit of hindsight don't believe I managed them particularly well.
One of the things being married (or living with a partner) teaches you is that you have to see certain behaviour as situational rather than personal. You've managed to suggest that (a) your flatmate cannot choose a suitable partner and (b) that she can make up for this, but only by paying.

Eugene, I think maybe English isn't your first language, so I'm not sure if you're being serious at some points in this thread. I've lived in shared rentals for years and years and it's completely normal to have people to stay. The difference in your bills will be negligible, so it's not worth stressing yourself about. You'll be so much happier if you just accept that some people like to take two showers a day, some people never cook, some people never watch TV, and some people have people over a lot, so the bills even out. If she'd suddenly started taking two showers a day and leaving the lights on when she went out, would you have wanted her to pay more of a bill contribution?

I don't really understand the safety issue, because you said, "It was ok for me until he started to spend 3 days and nights in a week in the property." What would your ideal outcome of this be, then? If he agreed to pay bills, or only came over two days a week, you'd still be feeling unsafe, surely? If he's actually threatened you, I agree that it's sensible to leave ASAP, and contact the police, but if you're just feeling uncomfortable around them because you've tried to ban her boyfriend from the flat then you might have to think of some more pragmatic options.

I think you can either find someone to replace you in the flat and move out or, if it will make you feel more comfortable and able to live and let live, ask your landlord if you can pay him to fit a lock on your door. If you want to leave your tenancy early, you usually have to continue to pay rent (for at least three months: it will say in your contract), or find a new tenant to replace you, because otherwise your landlord will be without rent and (ironically) your housemate will be left paying all your bills too!

thanks for the replies.
To Alicepalace
It is true that English is not my first language. Did it look like that I was kidding somebody putting my concern on the forum and asking for your help and advices?
As you noted “I don't really understand the safety issue... What would your ideal outcome of this be, then?”
My outcome is to follow the rules written in the Tenancy Agreement. If the Tenancy Agreement states that nobody except people mentioned in the contract can reside in the premises, it means that there is a breach of the contract. You can try to solve the problem by speaking to the other tenants and provide at least the
It’s all about the risks. When I said it was fine for me before, I meant, that up to certain point you can leave with those risks. When somebody visits (Visit not live) you flatmate it’s fine. But when you have to stay in one apartment with somebody you do not know for three/four days in a week and the doors to your room are open, then you definitely can’t say that you are in a safe place. The other issue, is that her boyfriend now have a key form the flat. According to the contract nobody can keep the keys except the tenants. Is it still ok? Definitely not for me. I used to live according to the rules and if I’ve signed something, I would not have to breach the rules. Certainly there are always such situations, when you have to come to the agreement with whom you have this conflict. Unfortunately we didn’t.

Alicepalace, excuse me my curiosity, how many languages do you know?

I am a part of a student community (PhD in particular), therefore I wanted to share with you my worry. Most of the replies were really useful and I’ll follow you advices. Sure, that a lot people from here appeared in a situation like this from one side or another. And perhaps some of you may face these problems in the future.

The key proviso is whether the 'reasonable person on the street' would agree with what your saying. Tenancy agreements can be widely interpreted so it's necessary to ask yourself:
(1) whether an ordinary person would feel it acceptable for a partner to stay over three nights a week (suddenly you're suggesting four days a week now.... let's get this straight, you need to keep a diary of these things). I don't think this is in any way unusual. Presumably she stays with him sometimes also meaning any additional bills are at worst, negligible.
(2) she has to put up with your friends coming round too, and trusts that her things are safe..... and lets face it, your friends are likely to be people you know less well than she knows her boyfriend.
(3) if he has a key that's another matter; if she has had a key cut for her boyfriend then you should make your landlord aware of that.
(4) there's no way you can really class him as 'residing' at your flat. As far as the reasonable man is concerned, the fact he hasn't moved his possessions in and isn't their constantly means this isn't the case.

To be honest, I'm not entirely sure what your bug-bare is. You suggest that merely by him being there you feel threatened, in which case your flat-mate is in a no-win situation. She could be having the pope over to stay, but according to your criteria this would be against the rules.

“suddenly you're suggesting four days a week now.... let's get this straight, you need to keep a diary of these things”
Just want to put the stress on my original post, where I stated “It was ok for me until he started to spend 3 days and nights in a week in the property”.
It is not suddenly, in average it is three days and three nights, whereas the maximum is 5 and the minimum is 2. Yes, I am keeping the diary since January 2009. Last year he didn’t stay over night at all, but last week for instance he spent 5 nights. Still not a resident?
“your friends are likely to be people you know less well than she knows her boyfriend” – true, but at the same time they have not used the shower here and usually I prepare tea and coffee myself, and they have not walked in the on the kitchen in night-suits.
And finally, he has or had a key. I could not check his pockets. He was able to enter the premises when she was not inside.

I don't mean to add to any disagreement here, but I think many of the previous posters are right - this is not as serious an issue as you seem to feel it is. Of course this is your home, and as such it is fairly personal, but it is your flatmate's home too.
A couple of things you have stated seem to suggest that you are fairly conservative in outlook (this is not a criticism, just an observation), for example when you note that they have worn nightwear in the kitchen. I don't wish to be a cultural relativist; but this is absolutely normal in every way; perhaps not where you are from or in your experience, but here it is. When I have friends/family to visit, even if they only come for coffee, it is also perfectly normal for them to make tea/coffee themselves (for example if I pop out to the shop etc).
Yes the situation is not what you had imagined when you moved in, and I can understand some annoyance at that, but people and situations change. An earlier poster noted that perhaps it was the manner in which you spoke to your flatmate and her boyfriend that may have inflamed the situation. Given some of the wording you have used on this thread it also seems to me that that could be the case. Regardless of who is right/wrong you (both) could have done things better. Perhaps yes, it may of been polite for her to ask you; but you should not have asked her boyfriend to leave - it would have been better to politely sit down and say to your flatmate that you'd prefer it if her boyfriend only stayed 2 times a week. In fact that is what you should do now. And then move out as soon as possible. For her sake and yours.

Ok, please stop being so defensive. I understand this is stressful for you, but we're communicating on the internet where, if English isn't your first language, it's especially hard for me to understand your tone (I was particularly thinking of the post where you were maybe joking about escalating a passive-aggressive war with her). I'm not saying the whole situation is a joke, but I'm saying that 1) you might not be familiar with cultural mores and expectations for flat-sharing (which is completely ok, and doesn't mean you have to live in a situation that you find uncomfortable) and 2) we might be misinterpreting each other in this medium.

This ultimately all comes down to cultural issues: you said it's normal for you to have friends over, to have parties; someone else might think it's normal for their boyfriend to stay over a few nights a week. If you decide that you are not comfortable with your housemate's SO staying over multiple nights a week, then you need to make that clear to your future housemates because, as Pamplemousse has said, it's normal behaviour and not in breach of the tenancy agreement (as evidenced by the fact that the landlord doesn't care). I appreciate that you're not happy with the situation but, legally and conventionally, it's you who will have to deal with it because your housemate hasn't done anything unacceptable. The conversation is going to be pretty awkward, because you're essentially going to be telling her that you don't like her boyfriend. Seriously, though, good luck with the situation because it sounds like a right pickle.

I think this post has really had it.

Key things to learn for future rental situations:

1. It is necessary to outline expectations in advance of moving in with someone. While this may sound very formal, it's likely to ensure that unsuitable co-letters don't get to the letting stage; i.e. if Person X wants a party twice a week and Person Y wants quiet study time every evening, there are going to be problems!

2. Pragmatism and negotiating skills (sometimes of UN proportions) are key to a successful house-share. This means dealing with things maturely. I look back on some of the disagreements I got into with flat-mates at University and am extremely embarrassed!!!
- Writing notes to one and other is never the best way of ensuring co-operation.
- Pay bills in a timely manner and agree how things are going to be split. If one of you intends to be away the whole Summer and doesn't think they should have to pay (much in the way of) bills over that period you want to discuss this IN ADVANCE.

3. Try not to get your Landlord involved in petty squabbles. You may have to rely on him/her for references in future, you want to be able to move out in a timely and efficient manner. If you nark them unreasonably then this may well prove an issue.

completely agree with pample, alicepalace. And yes, good end to an interesting (!) thread...