My boyfriend and I had the same conversation recently because I’m very very similar to what you’re describing. I don’t think he’s wrong. It really hurt when my boyfriend said it BUT I appreciate the gentle way he approached it and the fact that he said it in a motivational way rather than blaming/judging/etc. it stings like crazy but you have to remember that you feel the same way about yourself (like you’d feel sexier with losing weight) and he’s human and just being honest. I want to be the best I can be for him and to keep our relationship happy so I hope I can lose weight eventually (he understands the circumstances right now and assured me he loves me just as much anyway). My boyfriend is extremely fit so I think it amplified my own insecurity. It really hurt my self confidence because I was already feeling bad about myself but once I got past my initial personal hurt feelings (caused by my own insecurities) I was able to feel okay about myself again and realize that it was my own struggle causing me to react that way. I don’t know if that makes sense? I hope you’re able to feel better about yourself soon!