I think he’s cheating

Me and my boyfriend have been together nearly 2 years, he’s just recently got a car and even before that I suspected something. I don’t know if I’m being paranoid or what just I have a gut feeling. Things he says doesn’t add up about where he is and if he gets texts and his phone is in front of me he quickly deletes the text off the front of his screen, sometimes I even find marks on him like scratches or bite marks on his back and shoulders that couldn’t have been off me as I’ve literally got to the point where I’m not having sex with him anymore because I physically can’t bring myself to it because I have this thought of his being with someone else in my head, I also feel like he doesn’t enjoy sex, like he doesn’t make any noise or doesn’t moan or anything (which he used to do) so I feel that’s because he doesn’t enjoy it as he’s found better else where. Like I say he’s recently just got a car and I keep finding foundation marks on the inside of his car, like fingerprints etc. Which can’t be off me because I don’t touch my face when I have makeup on and he knows not to aswell because it’s a pet hate of mine. I can’t really talk to him about it because he’ll just go in a mood with me and he wouldn’t admit it anyway because he knows he’d never see me again and I just don’t know what to do. Maybe someone else has had this problem or something or am I just being paranoid idk??