Met a potential plate at a pool party yesterday. She was showing a couple obvious IOI's, but at one point she turned around to say hi to a male friend (obviously just friends) so I walked away and planned on talking to her later. But the party got broken up by the cops before I could do that.

She apparently knew my roommate from high school, but he's incredibly beta (and possibly jealous), and won't help me initiate contact again. I feel like it would be incredibly beta to send her a message on FB, but at the same time, I'm sure I'll never see her again if I don't.

TL;DR Met a potential plate at a pool party who was obviously interested, but got split up before I could at least get her number. My roommate knows her and is friends with her on FB, so should I message her? Or just forget about her and move on to the next?