It's my first time posting here so I hope I'm doing it correctly. Some background first: I met my ex through a friend of mine who was also at the table that night, we're not friends anymore but that's another story. It was summer 2021 and me and my friend, let's call her Angie, were meeting to go around the city, she was in a hangout group and she told me they were meeting closer to where we were. There we met my ex and we chatted about DnD and whatnot. We started dating at the beginning of October and Angie arranged a halloween party for our common friends where I invited my ex.
I told everyone who was coming if they wanted to play a one shot since we were going to stay for the whole weekend and they agreed. It was a homebrew adventure based on Lovecraftian Cults, and I even ran a test with another friend group to see if I could pull it off as a DM, which I was very excited to do. Everyone made their character sheet and everything seemed cool. Ex told me he was going to play as a journalist which I told him it was perfect for the story we were going to play. Imagine my surprise when the day of the one shot arrives and he has a completely different character from what he told me initially. Which, fine, you can change your character if you want but a heads up is appreciated. He didn't tell me anything btw.
So whatever, we start the game normally and everyone seems to be having fun and playing around the story I planned (we were all rookies at the table but me and Ex had a little bit more experience than the rest). Their characters were supposed to meet at a college party, everyone having their introductions and interactions like a normal game. Except my Ex. He was playing as a twitch streamer nerd who barely left his room and he joined the group much later in the session. Overall he wasn't participating, which I can understand since you're playing with people you don't know and you can be shy to roleplay and everything. But he wasn't even interested in talking with the rest of the characters and didn't interact with the plot hooks I was making up on the fly so that he could also be part of the story.
Basically, I was going out of my way to include him in the story, but all he was doing was roleplaying as a self insert of himself, aka, a nerd who didn't leave his room, and basically not participating at all, even though he told me he was excited to play the one shot. So after trying to include him in every way I could think of, I ended up killing his character. The one shot ended with the group finding out the college's cult due to his character being missing. He even had the audacity to tell me later that he didn't like the ending of his character because it was unrealistic that he got kidnapped by the cult when he didn't leave his room.
We broke up 5 months later for other reasons. I hope it wasn't too long of a post. Moral of the story: don't date incels.