I see this thread has evolved into a bit of a discussion on sexuality.
Still I think there’s more to your daughter than that. She probably has other issues stemming from her loneliness. Please encourage her to especially try and deepen her faith at this time.
Jesus Christ can fulfill all lonely places in the heart, and there are some even that ONLY He can fill.
Your daughter may not be open to the Catholic Church just yet, but try and find other groups she might join, books that might help her and music that might uplift her spirits perhaps?
Talking about sexuality with her might not be the best approach just now. Lead her to something beautiful, she’s searching!