QS, this isn't about sex - it's about her DESPERATELY needing to feel validated as a desirable woman, and she's going about it in disasterous, immature way.
A LOT of teenage girls do this. They hit puberty, get lots of attention from guys, and start sleeping around, thinking they're "all that," that every guy who sees them is dying for love for them. Their egos are boundless and any snide remarks are met with, "You're just jealous." Yet ask those same guys who love em and leave em if they'd ever take that girl home to meet their mothers, and they'll all say, "Are you crazy? I only introduce my mother to 'nice' girls."
This is so, so sad. I honestly think she needs help. She's jeapordizing both her health and her reputation.