First-Fuck-Syndrome (FFS)
When a woman loses her virginity, the resulting condition that causes an irrational feeling of attachement and love towards her current partner. The severity of this disease should not be underestimated. It can also extend beyond the termination of said relationship.  In unusual and rare circustances, it has been known to affect effeminate men as well.
"Wow, he told all her friends he hates her, cheated on her, got with her best friend the day after they broke up, but she is still telling everyone that she wants to be with him, and that he's perfect for her."

"Yeah, that girl is really First-Fuck-Syndromed."