So my boyfriend and I have been together for about 2 years now and within the last year or so he's started to choke me or rather put his hands around my throat while we're having sex. I don't really mind so long as I can breath. It seems like no matter the type of sex we're having, rough or slow, he has to put his hands around my neck to be able to finish. I asked him once why he does it and he said he didn't know, but to me it seems like he likes the dominance of it, maybe?

It causes me some concern because it seems like he can't finish unless he's choking me or pulling my hair or some act of dominantion. Has anybody else has/had a partner that does this?