I'm not sure if this is a bug or not: On my girlfriend's record, every time she sleeps, she gets one of the bed scenes with Gaia -- the same scene each time, like a flag isn't being removed.
It became a maybe-issue because when she reached the chuch in Grunfeld, she couldn't trigger the scene with Riliane, which IIRC on my own record happened after sleeping there. She just gets the Gaia scene instead.
(I'm not sure if this is intended behavior or not. It's possible we just ended up on different relationship paths, but we made very similar choices throughout the game and her relationship score with Riliane is at the best-friend cap.)