Because she doesn't have anything to offer. I'm on Ivy side, when it comes to her character judgment. It's nothing wrong with being a bit clingy in relationship, if you represent something with yourself beside that.
If you follow Lena size queen path, the whole naughty game night is set up to help go public with her fetish and sexually scout or probe Jeremy for Ivy. Either because him fucking around boosts his atractiveness in her eyes or she likes clusterfuck of social relations, before she finds somebody really interesting. So yes, lesbian experiments in public places, following fetish bliss without shame disguised as game of bottle or even shopping in adult store makes her enabler for Lena.
Ivy likes to slutify her friends through peer pressure. Jeremy tries to do the same with masculine part of the herd by trying to establish more hedonistic relationship standards.