She said that's why she gave it up
Lu is likely referring to a woman who legitimately tried to have serious devotion in a relationship but eventually gave up once she found out she’d been cheated on and resorted to similar behavior afterwards.
An alternative explanation is that she didn’t trust the guy but ended up giving it up anyway. Instead of waiting to build the trust in a friendship/relationship, she gives it up to him because that lust made it feel right, at that moment.
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