my boyfriend wont sleep with me

I mean, we've been sleeping together for over 2 years, bit the sex went from once or twice a month (too little for me), to once every 5 or so months (WAY too little).
He says sex is gross, but we watch porn and he talks about all the girls he's been with and would get with if he wasn't with me..
Is he just so unnatracted to me that he can't bring himself to do it? Other guys think I'm more than attractive enough for that, but aren't interested in much else.
I dont know what to do. if i try to be aggressive about it he thinks I'm being weird. i slept in a tank and panties performed oral, and masturbated twice later. all i ever get now is the pleasure of knowing hes enjoying it. I was in a tank and panties and he actually told me to put on some pants, like i should be ashamed of myself- when we've been sharing a room and bed for a couple of years, and have been intimate?
Of course, i dont want to leave him just because the sex is lacking, i just don't know if therea anything i can do about it.

not sure how this works so if i deviated from format or appropriate content- sorry