He doesn’t want to have sex with me

My bf of 3 years doesn’t want sex with me anymore. Our relationship is fine like he holds my hands and kiss me doesn’t act weird but like I feel like I almost have to beg for the dick and even then he still don’t want to do it. I don’t know why I gained a lot of weight I think that’s why I don’t know I am feeling insecure he don’t even touch me down there. It’s not a big deal but it’s a BIG FUCKING DEAL MAN I like sex and last month we only did it 1 time beCAuse I kept asking I’m just confused and I asked him why and he just says nothing or if we have sex it’s so fast and boring idk I’m just feeling some type of way