With the speculation that PhiPhi isn't a lover to Stephanie Jarvis, I am thinking that she might not be too interested in a sexual relationship? She was very attached to her father(non-sexual) and maybe her partners have been a letdown?
In my opinion, she gives off ambivalent vibes towards men, I know she flirts, I know she belittles men, I know she does the femme fatale thing, but it doesn't come across as a sexual attraction to men. She could be afraid of a sexual relationship? One-night stands have apparently been regular. The cosying up in bed with Ollie, Michael P., PhiPhi, whilst eating food/drinking and giggling, is probably all she wants. Childish high school stuff, which attunes to the little girl who never grew up narrative she loves.
The come duck me clothes she wears are all too try hard and useless; she doesn't seem to know how to attract men. She is a teaser.