> As a grown adult, having roommates is not really an acceptable situation.

I know plenty of grown adults that have roomates, because they prefer the quality of accommodations they can afford that way to what they would be able to afford without them. (And not even in places with Bay Area-level high cost of housing.)

If it is unacceptable to you, that's fine, but don't pretend it has something to do with being "a grown adult".