General

There's a 99.98% chance that those are just fantasy scenarios in an erotic fiction. I also read a story about someone using a spell to exchange their fat with someone else. Probably a good chance that hasn't actually happened IRL either

Being secretly fattened in a relationship has certainly happened. But probably in smaller quantities. Cuz I mean, you're gonna notice sometime, right?

It's a very rare case to just trap someone in their home and make them immobile. Like, 1 in a billion. Early internet model Teighlor was a victim of this. Her partner just left her on her bed with snacks all day on the second story and she got stuck. But it's rare. Most people in that situation are there because of other reasons, like addiction, mental illness, a nonsexual enabler. Very few people at that weight are there for sex reasons, and among that group, it's practically nonexistent to see someone there nonconsensually

There are definitely people who have been fattened secretly by abusive partners because they don’t want them cheat/leave them or because they are fetishists.