In a fit of spite with him, she decided to start having sex with all three of them. This was a no big deal thing to her. (I learned this when we all sat in one area with no cubes. There was no privacy on phone calls.)
She is 21, attractive and Daddy has big bucks, for what it's worth.
These people think of sex as a pure biological act having nothing to do with love and commitment. They can get it on with some stranger walking down the hall, and think nothing of it.