My sweet, gentle, loving boyfriend *really* enjoys strangling me...

My partner is one of the most loving, sweetest, most gentle young (he is 20, so is younger than me) men that I have ever met. He is considerate, empathetic, caring, he cooks he cleans.. all the good things a girl could want in her sweetie. We are not only very much in love, but we are also best friends, which for me, makes what we have, very special.

I am just wondering though, is it normal that he >really< enjoys strangling me? I don't mean like 'play choking' ... he actually likes to leave deep marks on my throat, bruises, and gouges where his nails have been digging into my neck.. though he will usually kiss me while he does it and tell me how much he loves me, even when I obviously cannot breathe (which is most of the time!)..

..and, it >isn't< during sex; more just, when we are being loving and intimate with each other (clothed) like, during foreplay, except it doesn't actually lead to sex.

I don't mind it, just so we are clear. Although I do not receive actual pleasure from it, I enjoy submitting to him in that way, and keeping the bruises/gouges covered from other people is something I find very arousing in and of itself.

oh and he NEVER would do it in anger.. he doesn't get angry really. He wont ever even argue with me.. if I am angry at him (which only happens rarely anyway), he will just sit there and say how sorry he is, even when he knows he hasn't actually done anything wrong.. so, he is like >the worlds< most non-grumpy person, if that makes sense? anger is just not something that comes naturally to him...

I did do a google search, but mostly all I can come up with is people who enjoy >being< strangled, to enhance their sexual pleasure or whatever.. he does not enjoy being strangled, though he said he is happy for me to do it to him if I want, which I don't. I also asked him, out of curiosity, what it is he enjoys so much about it, and he said that he absolutely has no idea; emotionally, he just >really< enjoys the feelings he gets from strangling me, it makes him feel intimately connected to me, and deeply satisfied..

sooo, is this a 'normal' thing for him to want to do to me? Is strangulation something regular, that males like to do their lovers as an expression of their love, rather than as an act of anger?