Told Myself He Had to Go

So there was this guy at work who I thought I had feelings for until one day, he asked me out and I politely said no. Since then, every time we're in the same room together, I feel like a liar. We still talk and act friendly, but inside, it's like I'm keeping a secret from him and myself. It's not even romantic, I just keep convincing myself that what he sees as interest is really nothing at all. But it feels kind of petty to pretend there's no weirdness between us.