For some reason the "Ask To Move In" interaction will not appear in my game. I have tried it with many different Sims but the action will just not appear in any of the menus.

I have to manually go into "Edit Town" mode and combine the two households, it's very annoying.

Any ideas?

Sims have to be really good friends for this option to appear; so try doing a lot of 'friendly' interactions. Also, some traits can affect how fast sims become 'best friends' with each other, if you have the 'friendly' trait it's easier.

If this doesn't help, then I'm at a loss as wel..

I can eventually get the "Ask to move in" interaction after doing A LOT of friendly interactions and ONLY friendly interactions. I mean, don't throw a funny or romantic one in the middle. They don't have to be best friends, although that might help, but I've had just Good Friends move in. It takes a lot of friendly interactions though, hopefully you can get it to come up.

i dont even really need to be good friends with the sim before i get the option...thts strange tht its not working... maybe its just a glitch?

That's right, you just have to do lots of friendly interactions until the other sim thinks you are friendly. Always works for me. I think it should also pop up after romantic interactions, too bad it doesn't.

It seems to be very very rare that the option to move in actualy appears.
I'm hoping they will make a mod to fix this.
The best thing to do is to marry them and then you can move them in
but i normally just use edit town as well

I came to this section of the forum to ask the EXACT same question. I want my sim's boyfriend to move in with her, but all I've been doing is romantic interactions to the point where they woohoo. I thought that would work, but it doesn't.

So, let me get this straight. Sims can move in together with ONLY friendly interactions? That's stupid.

Yeah, it is not very logical. But it pretty much always pops up for me after friendly interactions, the sims don't even have to be good friends. By the way, some of my teenagers have been rolling wishes to move in with their boy/girlfriends - is that possible?

I think how it works is,
regardless of whether they are bf/gf/friends whatever
use plenty of friendly interactions before u want them t move in
and then the option should come up

I've tested my above theory and it worked.
Two of my sims who were bf+gf used friendly interactions for a while and the option came up.
Try it

It worked for me.

I normally have it pop up after asking them if they want to stay the night.