UNSATISFIED. HELP

My boyfriend of 8 years recently lost his sex drive. He says it’s just because he’s more mature, but I don’t buy it. I’ve gained almost 30 lbs due to birth control, I have new, dark, huge stretch marks ALL OVER. I caught him cheating online over a year or two ago and an old phone was FILLED with nudes, conversations, everything, so forgive me if I don’t exactly believe his sex drive just *disappeared* for no reason.

We used to have sex almost daily. Long, hot, and pleasurable sex. Now, I’m lucky if I get it three times a month for longer than five minutes a time. Now, don’t get me wrong, I completely understand if he doesn’t want to have sex everyday, or even every other day. He’s entitled to say no, but what I keep getting hung up on is the WHY?! He won’t tell me anything. I don’t believe he’s cheating again because his email is on my computer, and would get a notification whenever he logged into a fake Snapchat.

On Valentine’s Day he knew I felt like shit and just wanted something, so he fucked me hard and good, and god damn it only left me wanting more. It’s nearly two weeks later and nothing else has happened. Any time I try to initiate something, he turns me down like I should be grateful I got what I did on the 14th. I would be happy with sex once or twice a week for 10ish minutes because then I could at least feel close to him and be able to cum. I’ve talked to him multiple times and nothing changes.

I can’t exactly masturbate because he tells me to, but wants me to make sure he isn’t interested in sex first, but if I check and get turned down, he knows I’m going into the bathroom to finger myself and it makes him feel like shit so he’ll get angry and annoyed with me. WHAT DO I DO