The dynamic of master and slave romance is troubling. it can spark forms of Stockholm syndrome and a bunch of other things. i'm not gonna go into all the details because fuck you, you look them up.
When catching a pokemon, you are taking away its freedom and conditioning it in to liking you. by doing this you are no better than plantation owners. to add more to the fire, pokemon are considered animals as people eat certain pokemon such as slowpoke, magikarp, kingler, barraskewda, and plenty of others. In johto it is deemed cruel to eat slowpoke tail but in galar it's fine.
Wanting to marry or be romantically involved with a pokemon makes you a genuine food fucking faggot or a fucked in the head plantation owner