I don't know what to put here

So I've been with my partner nearly 3.5 years now, we are very much in love, we don't have any problems with our relationship, sometimes we argue/bicker but we've never had a fight. We used to have sex at least once everyday and it was fun! We've lived together for about 2 years now, and since we've been together I've put on about 30kgs. He still loves my body, and is always turned on by me, but I find that I don't seem to want to have sex now unless I'm drunk. I still get horny and will masterbate alone, but I just don't want to have sex, and if we do it while I'm sober, it just feels like a chore, and I want it over pretty quickly. Has anyone else been through something like this? Idk if it's because my mental health is bad, or if it's a self confidence thing, but I still really love him and I want to be able to love him physically too, but I just never feel like it. He never makes me feel bad or asks for anything sexually, so I'm not being pressured into it. But idk if this is a normal thing?