Girl likes guy, guy likes girl, but won't act on it....so why does he get mad when she moves on without him?

I told the guy I like how I feel about him and he expressed that he had the same feelings for me, but he won't ask me on a date or try to get me to be with him, so I've decided to move on with my life. There is no one else. I'm just tired of being in limbo. Now he's all upset that I don't talk to him and that I'm moving on. Why? He knew I wanted to spend time with him and I gave him every opportunity to step up to the plate and he didn't.