This is a classic case of Alpha males vs Beta males. In the animal kingdom, Alpha males generally get to mate with almost all the females in the herd. Females evolve to desire males with Alpha traits, such as confidence, power, and status. Alpha males are bold and not afraid to talk to girls. They don't worship girls the way Beta males do, they make fun of them instead. Alpha males can have a temper and will fight if someone challenge them. Jocks, Jerks, and Bad boys generally are Alpha males. When a girl detects a Alpha male presence their panty gets wet. Ex #1 is a Apha male. Beta males however are generally weak and submissive. They are timid and usually avoid confrontations. Beta males worships the ground that females walk on, they are the doormats, the nice guys and the white knights who think their good deeds will attract the female. But it won't. When female detect a Beta Male presence, their instinct tells them he is "yucky." Now, why would girls want Apha males who might cheat on them? Because they want their offspring to inherit those strong traits. They are not making this decision consciously, it's all happening subconsciously. Now I want to clarify that being a Alpha male doesn't mean they are automatically going to be bad or unfaithful. There are good Alpha males out there too, they are the real men. And most women want a real man. This is why the girl find ex #1 more appealing than you. And why is she still so close to him even though he cheated on her? Because she's not smart enough to avoid such a douche-bag.