Fogg said it so well...balance. I wish I'd come up with the word when I was struggling with how to advise.
I have to say, borrowing from Fogg again, when I pictured you in the role of "Gay Boyfriend", I might have snorted some water out my nose! That's too funny. You could use that with her next time she expresses a desire to "just be friends." You could arch an eyebrow, give her a lopsided smile, and say, "What? Like a gay roommate?"
I hope you're laughing right now. I know I am! My youngest brother, who really is gay, would be rolling his eyes at me right now. He finds my sense of humor "taxing".