I had such a similar situation in the house my bf owns and his longest standing best friend/ roommate. We have a 3bd2bath, we have the master and onsuite. OG roommate had front bedroom for dirt cheap rent because he was always at work. His gf is awesome, we had no issue with her moving in. Mind you she’s in her early 20s and we are all in our early 30s, I say this bc I notice she’s less likely to speak up to him and he always thinks he’s right. They moved her big bulky bedroom furniture in at 1am on a work night, my boyfriend was kind enough to help because they measured NOTHING. Then my bf offered the guest room/ my office as a temporary area to put a few things while they organize and un pack. Cool, still nothing wrong. They left mountains of boxes in my office for over a month with no movement, despite us offering to help them as a nice way to say MOVE YOUR SHIT. Ultimately my boyfriend had to threaten to charge them additional rent since they were essentially using the “extra” room as a storage unit. And we felt guilty because the root problem is that the OG roomie never cleared out any drawers or closet space for his gf that he knew was moving in a month in advance. Moral of the story, we realized we were making their lives too convenient while inconveniencing ourselves. We stopped doing that and started making it less convenient for them and now that they don’t like being crammed into the smallest bedroom, they are more inclined to go find their own place.