Why do we like people who ignore us?

Women seem to be attracted to men who blow them off. Men seem to be attracted to women who "play hard to get." What is it about people that makes us so drawn to those who pretend, or perhaps really don't, want anything to do with us?

Becos people like a challenge, we like to see who we can and cannot get. If there is this sweetheart guy who would drop anything to go out with you, and then theres this bad boy who doesnt return your calls, the sweetheart looks to easy, we'll go after the bad boy who ignores us just to see if we can get him. Its so wrong and I dont agree with it, but thats the way it is these days, the people we think we cant get are more appealing becos we want to see if we can get them anyway.

humans like challenge's.

Both of these answers are incredibly stupid. Sorry to be blunt, but it's true. If you want a challenge, you try climbing a really steep mountain, or increase the difficulty setting on your video game. But looking for a relationship with someone who blows you off just to challenge yourself is a sign of immaturity. Anyone else?

Because it makes us think they aren't going to be needy or make demands on us--obviously they have enough going on in their lives already. Which is also intriguing--just what do they have going on that's currently more interesting than sex?