How do I know if another player approves of his/her sim moving into my household?

Not too long ago someone wanted my sim to move in, I declined because I like my sims. I don’t retire them either. But I felt sort of bad just declining and I don’t any way of saying sorry I prefer to keep my sims.
There really should be an in-game PM system.
Actually there’s a lot of things that can improve this game that haven’t gotten implemented. EA seems to busy coming up with the next money making idea rather than the next game improvement.