I’m not good enough...

I have been with my boyfriend for 7 years now. He is 21 and I’m 20. We have sex about 3 times a week. We don’t live together so when I’m not with him he decides to watch porn... I have told him that I don’t like it when he does that but he just tells me that there’s nothing wrong with watching it. I can’t help but feel like I’m being compared. Also why can’t having sex with me 3 times a week be good enough...I recently gained weight and I feel so insecure. I’ve told him about it but it doesn’t seem to change his mind about it. I constantly look at myself and feel like I’m not perfect like those girls in the videos. Any advise on how to over come this insecurity. Or how to deal with this situation..? Thanks!