My wife went to school with someone from a popular TV show a few years back, where she'd be in sex scenes fairly frequently (from what I hear, I watched a few episodes and hated it). She had a long-term boyfriend at the time, and it didn't take long for him to not be cool with it.

She also went to school with a musician that had a stab at a solo career. She had some raunchy scenes in a music vid, and that quickly led to her breaking up with her boyfriend.

Those are my only two frames of reference, but I imagine it's quite hard to deal with emotionally, even if you know it meant nothing and is just a part of the job.