I'm having the same problem :(
It was an option before and now that I found someone I want to move in... I can't figure out how to do it!
Silly old fashioned me - I just want them to be in the same household before they have a baby LOL
I have the same exact problem. I’m on level 10 and I’m married and I still can’t move my husband in. I have another room mate and I’m trying to get them to be good friends so I can move him in that way