Here's why
women want you when you're
taken:
You're taken.
Some women see a man who is taken, and think to themselves,
"Hey.. this guy has a girlfriend. There must be something good about him worth having. I think I'll attempt to make a move."
Not all women are like this, but some women, either conciously or subconciously, think like this. Some women want the challenge that going after a man who is taken brings. Some women are just dysfunctional.
There's a reason people say "all the good ones are taken". People covet what they can't have.