Girls might not always know he has someone. Guy can go around playing that he’s single when he’s not.
Also, while girls who purposely go after married men are bitches, they are not in any relationship. They dont have a spouse/other, or a child or anything, the married man can also say no. Also, men will cheat b/c their wife isn’t satisfying them (in some cases). That’s not always the case, but it is something to ponder…