Don’t get me wrong, I love my boyfriend but....

Am I wrong here? Should I even feel bad? Or should he? We’ve had our share of problems along the way of our 4 year relationship. Many ups and down to say the least. Sometimes he’s amazing and loving, but most of the time recently he’s monotone and sounds like he rather be anywhere else. He spends all day with his friend and pays very little attention to me. Hell, he’s not even that nice to me recently. Unless he wants sex... but why should I give him what he wants? I don’t get what I want! A loving boyfriend who shows me that he still wants to be with me. A relationship where I feel wanted. Respected. Loved. It’s the most depressing feeling in the world knowing that he’s only being nice to me because he wants sex from me. And then he’s only nice to me for a minute or two afterwards. Then he’s right back to acting like he has better things to do. So why should I sacrifice my happiness and mental health so he can have his couple minutes of pleasure? I rather just skip the whole thing rather than feel like a used napkin with no other purpose when it’s all said and done. Just tossed to the side. But if I don’t give it to him, he gets in this super pissy mood and shoots me attitude (when he’s not ignoring my existence). Which he swears he doesn’t do, btw. And yes, I have tried to him. He swears like he understands, yet makes no effort to change. How is that supposed to make me feel? He understands that I feel neglected, yet he doesn’t do anything to solve the problem? Interesting logic. But this is love, right? According to him, he wants to “be married and be together forever”. But how can you love someone and KNOWINGLY make them feel like this? I mean, I dont even know where to begin? Any insight on this situation from an unbiased source would be wonderful. I don’t want to leave him. But sometimes I feel like that’s the only option. Thoughts???