Most Helpful Guys
Guys lie, girls lie. Guys change their minds, girls change their minds. This is a two way street. I'm sorry for your friend but it's untrue that this is just guy behaviour. Girls stab guys in the back too, all the time. People can be selfish.
*Some Guys, why do you insist on hurting girls?
Because those guys are not very nice. Or it wasn't his intention and he didn't have mutual feelings.
Most Helpful Girl
Because girls put up with it. I got dumped by my now ex, and told him to fuck off and never, EVER speak to me again. So far, he has not done so. Peace!