Am I overreacting?

Me and my boyfriend have been together for almost a year now. I love him to death and I know he loves me. We have a very active sex life and pretty much every day. However, he takes forever to finish, and a lot of the time he’ll watch porn while we’re having sex to get off. I’ve noticed over the last couple of months he has been doing it a lot more while we’re having sex, and a lot of the time without it he loses his boner. I feel like he’s not as attracted to me anymore, and so he watches porn to get him off instead. It wouldn’t bother me if I wasn’t there and he wanted to masturbate, it’s his body and I’m not going to be that girlfriend. However, I hate that he does it when we’re having sex because I’m right there yet he’s thinking about other girls and it’s turning him on. It hurts my feelings and makes me feel like I’m not good enough sexually or physically. I’ve tried confronting him about it and he just tells me it’s in my head. But nothing changes and it honestly does kind of hurt. am I overreacting about him doing this?