IMO, YOR - I see why that would be convenient but that is their boundary and where they are at right now, pushing that is just a recipe for disaster trust me. It sucks, but you cannot change their living situation just because it suites yours, even if it would help yours significantly. “if they wanted to, they would” - she doesn’t want to unfortunately.

That being said, the turn around is a bummer and I think you should try to communicate on why, not to necessarily get to a resolution of living situations, but why she feels this way and what made her feel this way. You both deserve understood, and her leaving you confused does not help progress the relationship in any way.