Yeah, that was the part I liked as well. And it made my brain hurt for a second to think how that worked. It sounded like a bad rumor.
But, it makes perfect sense you have to think about it
A girl is loath to date her old boyfriend's new girlfriend's old boyfriend
g1 = girl available: this is the girl that is looking for a new boyfriend
b1 = this is the ex-boyfriend of g1.
g2 =this is the current girlfriend of b1 and ex-girlfriend of b2.
b2 = boy available: this is the boy that is available.
Now then let make some simple hypothisis
g1 thinks that she is better than g2 hence g1 > g2
if that is true then g1 thinks her decisions are better than g2 therefore anything g2 likes has less value than what g1 likes.
Following that g1 thinks that b1 is better than b2 because she picked him first if not then she would have picked b2.
Now then if you think about it b1 is the alpha male becasue he can command the attention of two women.
b2 is the lowest on the social chain becasue g2 doesn't want him and g1 wouldn't bother with anything g2 wouldn't want becasue g1 is "better than" g2. Women's prime motivator is finding a mate that can provide for her. If b2 couldn't provide for g2 then what good would he do for g1?
Now then the reverse doesn't apply for men because as we saw in the Monkey study a male will pay to look at any woman's ass.