The problem

I met this girl online in the dating category, but she wanted to have sex right away.
Being a guy, naturally I wanted to and did have sex with her the first night.
It messed me up because she ended it a few days later when I texted her, said
she had a boyfriend and the relationship was working out again, blah blah blah.

I didn't text her too much, she kept telling me how much she liked me when we were together,
what did I do wrong?

- Sandy