juju really you need to get your ex out of your head and out of your bed.
Its the no.1 crime here - holding onto someone, thinking the chemistry is so good that nothing can beat it, sadly in my experience the chemistry blinds you to the bad parts!
I had chemistry with this financial person (Paul) - too much, and it was only when I texted him in a fit of madness that I'd cheated on him (we were on a break!) and something else nasty that I thought after that, I can't contact you again (like I did before) as if he replies I will think what a mug and it just gives me a reason to treat him like shit.
Kent Lad - chemistry there too, too much etc but I know that I'm too good for him and he will never ever change. Also I'd be stuck in that pattern of "so will you change ever?!" and of course with men like these (40-something tend to be harder at committing etc) they won't.
I should have known with Paul that when he told me on our 1st date that his friends told him he'd be "the last person in his group of friends to get married" that that showed commitment issues, plus his parents' acrimonious divorce which really affected him (he talked about it a lot).