Late night thoughts I need help..

So my boyfriend and I have had problems having sex, it’s mostly all his fault. Let me also say he’s 25 I’m 22 and I know he isn’t cheating. But he does not try, no matter what time of the day. If I touch his dick he’ll have an excuse or say no I’m sweaty down there, let’s do it later, or he’s tired, or there’s always something. I will rub his dick until he gets a boner but there’s always an excuse why he doesn’t wanna. In the beginning of the relationship, he begged for sex all the time. Ate me out, fingered me had foreplay and did different things even when I was tired. Now, we have sex once a month maybe, and it’s on his terms. Before we moved out, I said it better not be like this and he promised it wouldn’t bc we would be alone. We have been moved out for almost a year, sex has been less than I ever imagined, I hate it and he knows it and OPENLY does the same thing every night. I have shown him my lingerie, and put his hands on me and he’ll grab me for two seconds and carry on.. literally will get a smirk and a grab that I initiated and that’s about it. But here’s the kicker, not only is sex on his time, but he watches porn... like how are you going to watch porn but have sex with me once a month with EVERY excuse in the book?!? Idc about porn but when you’re fucking once a month there’s clearly an issue... he knows I’m deprived. & just a note, I’m not open to watching porn during sex, he’s never asked and I wouldn’t be comfortable. Anyway, I also told him I will not be the one trying since I’m always getting shut down anyway, well that has not worked for me I just feel like shit now that I’ve gone on his phone to see that he’s still been watching porn and liking girls pictures. Just sad how he doesn’t have an ounce of sexual desire for me but anyone else can have his attention. I’ve been dealing with this incompatibility issue or porn addiction or which ever you wanna call it for way too long. Is it worth it to break up over after 4 years? Not everything else is great but we obviosuly havent broken up yet, I still love him. But I hate feeling so undesired...