They met 23 years ago. She'd been heavily sleeping around until then, but that stopped once she met him. She tells him some of her past, omits some, denies what later comes out as true. They adore each other, tho and marry one year later. Over the years, the cycle of lying, then admitting continues. Sometimes she changes her stories several times.

To make things worse, she seems to have a need to continue to flirt with men and seek attention from men. She follows them around; she makes fake doctor appointments with cute doctors; she receives gifts; she sets up social events for both of them with men she likes, but says it's because she thinks he'd make a new friend - the list goes on. AND she admits to these events in same way as her past - denies, lies, admits, changes stories, etc.

In the meantime, he treats her like no other woman has ever dreamed of - he includes her in every aspect of their life (he doesn't go out with his buddies, etc.) - they have an incredible sex life. He is attentive and loving, although hurt and angry at her behavior. She falls more and more in love with him every single day, yet she still has to get this attention from other men.

In what is otherwise an incredibly beautiful and special relationship, this has caused a great amount of pain and mistrust. He simply cannot believe she has remained faithful to him. He feels that if he could just understand why she did this (which eventually stopped after many years), then maybe he could accept and believe in her fidelity. But she can't explain it to him because she does not understand it herself. If she did, she'd explain it to him.

So what happened? What is her gain from this behavior? Any ideas?