Hi everyone,
Thanks for all your advice! I've taken on board everything that's been said. A few have you have asked if I'm sure my feelings for him are actuallu love and not some silly little crush taht will go with time- don't worry I didn't find it patronising! I've considered that myself- it could just be about the power dynamics and the fact that I really admire him intellectually etc and it will pass once the Phd has been finished. So it could be "love" or just a daft crush- to be honest I'm not sure, but I think its become irrelevant because regardless of the nature of my feelings its distracting me. Hence the decision to change supervisor!
However, somebody said (sorry I can't see the names as I'm typing this) that even if I did my best to keep my reasons a secret the truth has a way of coming out. Which is unfortunately probably true- particularly in my department which can feel like Heat magazine at times :-)
Also, I have possibly been spending all my eenergy on the PhD and maybe neglecting other areas of my life- so maybe its just a case that I've nothing else to think about. I've spoken to my friends about this obviously but none of them are studying so they felt like they weren't in the best position to offer advice.
So, I've decided to hold tight for a while, say nothing to anybody, get myself a life :-) and see if this resolves itself.
Thanks again to everyone for taking the time to reply!