If a guy likes you and pays attention to you and later on starts ignoring you?

The guy pays the bill in respect unless it's two female then I have no answer

In my experience if I stop ignoring a girl that means I'm not interested anymore.
You might label me as young and stupid but for some reason once I find out that a certain girl I like, likes me too, I tend to back away and go for someone else. Kind of counter intuitive and I don't do it on purpose but looking back on it, I do it a lot.

One of two things:

1. He thinks he was too honest with you and is now embarrassed and trying to hide that by ignoring you

2. Your response when you found he likes you was too straightforward and he's backing off cause you gave him too much attention and high school guys are immature

He might have gotten a new girlfriend!