Low sex drive and jokes about not having sex

Me and my BF have been together for a little over a year now. When we first started dating we where haveing sex about 3-4 times a week. Now we barley have sex once a month. It started causing a lot of problems when it first happened, but now he says that he's ok with it. I think it still bothers him but he just doesn't want to upset me. I tell him it's cause I think I have a low sex drive but idk if he believes me. I feel bad because he tries to initiate it more often than I do and I can tell he gets his feeling hurt when I turn him down. He also started making jokes about how he will just have to wait til next month cause he missed his chance this time and I've told him that I don't like them but he keeps making them. I guess what I'm trying to ask is does anyone know how I can maybe up my sex drive and if anyone know how I can talk to him again about stopping the jokes?