This is a phrase that I have heard often, but I find that a lot of people either have never heard it, or don't agree with it. These are usually the type of people who haven't dealt with much rejection in their life, and don't know what it's to be truly hated. When you get right down to it, it's a very juvenile reaction to an emotionally volatile situation. If you can't deal with your feelings about a person, you turn around and try to push them away by hating them.

This sort of thing can be blatantly seen after a couple has broken up. When they see each other again, for the first time after they've been apart, they usually try and act like they haven't been thinking about each other. Usually, even if it was a bad breakup, they try and make it clear to the other person that they have been ignoring them. It's a quirk of human nature.