Boyfriend doesn’t want to have sex with me

So I’ve noticed this getting worse over the past year. He will reject most of the time when I try to initiate saying he’s tired or doesn’t want to. Atm sex is very much whenever he wants it. The worst part is I don’t want sex or any other sexual acts for my own sexual pleasure I want to do it to make him happy and myself feel wanted as I am rather self conscious since going from 8st to 10st and struggling to lose weight. Idk if this is the cause of his disinterest but I can’t help but feel it is… idk what to do or say help?