Our sex life sucks he says

My husband tends to get tired on the middle of sex, and loses it. He also get abdominal cramps. Hed get so frustrated and blames it on me. He says it a lot that our sex life sucks, it doesnt even feel good, our sex life is stupid, always makes him tired, he never get anything good out of it. Its really making me feel like he just doesnt like to have sex with me. But if it was someone else, hed love it and itll feel good for him. This making me feel so low about myself! Looking at it, its not even me! Its him! But idk why hes blaming it on me! Is it because if he does it to someone else, hed feel more good, excited, wont get tired, and wont get cramps? What kind of fking shit is that?