Just Can't Get Enough of Her

I met this girl at a grad school mixer last year. We hit it off instantly and started seeing each other casually. The sex was great, but the relationship got complicated quickly after I split with my ex-wife. She's in her twenties and knows exactly what she wants, sex without strings attached. After we had some wild CNC sessions, she left me feeling both fulfilled yet unsatisfied. Anybody else struggle to let go even when they know it’s not right?