Get Friend to Move In With You

Why is getting a friend to move in with you so difficult? My sim Melanie began a relationship with the maid, Ronny. They were good friends, so I advanced it to boyfriend/girlfriend status. I think this was when Melanie was a young adult, and who knows what age the maid was.  I moved her out of her parents’ house so she could go live with Ronny, and she has a wish to ‘Move in with Ronny’ but the option never becomes available. I can’t find where he lives in the neighborhood in order to merge the households manually, so I think he’s a ‘Townie’. Is this the reason they can’t move in together? Or perhaps he’s still a young adult while she’s an adult now, and he’s not allowed to move in yet. I’ve read on Yahoo Answers that you just need to do numerous romantic interactions to get the Move In option. I’ve done this before with Mortimer and Bella Goth and it worked. But I don’t think they should have to be in a romantic relationship in order to move in together; the Sims 2 game allowed the interaction as long as they were good friends, and it seemed so much easier. And it was very easy to make a Townie move in with you, as long as they were the right age. I did turn off aging so I could work on this issue, but maybe I have to wait until Ronny ages. How can I tell if he’s a young adult or adult?

Also, how are you supposed to know when you’re in a relationship with someone who’s much older than you? I wouldn’t want to get married to someone if they’ll soon become an elder and won’t be able to start a family.  Relationships without the Story Progression just seemed so much easier.  You knew what age everybody was. Along with the issues with disabling Story Progression, and I’m getting pretty annoyed with the bugs in this game!