Boyfriend masturbating instead of being with me?

So background: when we first got together me and my partner were long distance. When we first saw each other, we would mutually masturbate and not do anything else. Since been 2 and a half years of this and now we live together. Never had sex, won’t let me do anything to him really except touch him sometimes. I want to, he won’t tell me why. I would want to have sex. The mutual masturbation thing has also gone down in frequency, we used to do it everyday when we met up (long distance), then every subsequent visit it got less. Now we live together it can be up to a month before we do anything. I just thought his sex drive was decreasing and didn’t push it and thought well not gonna force him. It did give me confidence issues when I talked about it around the year mark when he didn’t want me to touch him very much. He also always makes excuses as to why he doesn’t want to do anything, barely initiates anything and he acts like I’m trying to when I try and kiss him (sometimes I try but most of the time I just want to kiss my boyfriend goodnight!)

Cut to yesterday: I found fresh like moist cum stains on our bed just before we got into bed. We hadn’t done anything so that means he’s been masturbating during the day, whilst working from home. It felt like a gut punch. All those feelings came rushing back of feeling inadequate. I confronted him and asked what it was seeing if he’d admit it. He denied even knowing what it was and even denied spilling anything. I haven’t spoken to him properly since, I can’t eat, I’ve just been crying. I don’t know what to do I can’t even look at him or think about it without crying. It’s not cheating but I just feel worthless because he won’t do anything with me, not even initiate kissing most of the time. and makes excuses etc. just feel like somethings wrong with me.

Just any advice or comfort would be nice if you have any, or just tell anything.