Ugh, this is... very relatable. Even beyond the inherent crappiness to people who are fat, it's... dehumanizing/monsterifying of people who find them attractive, in a way that's almost impossible to talk about because being attracted to an ordinary way a human body can look is automatically considered a fetish.
IDK, I just don't think I can verbalize how badly the cultural attitude of "not only are we going to treat your partner like an inherently awful person, we are also going to treat you badly for daring to have affection" messes someone up.