Idk how to feel anymore

So I’ve been with my boyfriend for 15 months now but for the past 3 months things have been changing, like he doesn’t want to have sex as much anymore. Like I feel like I wanna have sex everyday & that I am begging him to have sex with me. Before we would have sex everyday then it turned in to 3 times a week, then to once a week now it’s like 1 every month or once every 3 weeks. Like he always shuts me down & now I’m starting to feel like he doesn’t love me anymore or he’s ashamed of me or my body or that something is wrong with me. & when I bring it up he gets mad when i say “ why don’t you love me anymore like did I do something wrong “. Then he always comments on my weight on how that I’m losing to much weight so then i started thinking it was that like he’s making me feel insecure about myself. I love him so much but i just don’t know how to feel anymore & I know sex isn’t always Important in a relationship but it’s a big factor to me. We are with each other day in & day out due to our city being shutdown again so I would think we would have more sex but nope won’t even let me give him oral. Is he cheating ? Like what is it