Crap.
I'm not completely sure what that means but I don't think so. The other sim he's living with has been transferred from one neighborhood to another, and I was lazy so I just moved her to the simbin and then to the other neighborhood.
I figured since I barely had made any progress with her (I had just moved her into an apartment and decorated it when I realised I wanted to use another neighborhood), I did it the easy (and wrong) way. But the problem is with the sim she's living with. He was originally made in the "right" neighborhood and I haven't done anything strange. I think the problem started when he was a plantsim, I'm not sure. Or when I made him a human again.