Funny you should say that, this was done to me.
I have a group of friends, we all like videogames and fanfics, but it used to be bigger. We liked to write fanfics about each other's OCs, but there was one guy that decided to write about us specificially. And instead of focusing on the group becoming tokusatsu heroes so we'd laugh over inside jokes, he decided to pair people he thought had chemistry, including me with a guy that at the time was sexist and FAR younger (he got better), people that were in relationships with people other than their partners, and weird romantic scenes that made everyone uncomfortable!
Granted, we were all teens, but nowadays we mention that fic with nervous laughs and hopes that it'll be the last time someone writes meta humor involving romance.
So yeah, no, disgusting, please don't write romantic or sexual fanfics of real people. Parasocial relationships are a real problem and other human beings are not your toys.