Why is he continuing to flirt?

A coworker of mine and I have been friendly for some time now. Recently we admitted our feelings for each other, but in that moment he had stated that he doesn't date coworkers. Since then, he has become a lot more flirty. I've tried to keep it cool because of his wishes, but this increased flirtiness makes no sense to me. Why state that you are backing down, and then do the complete opposite?
Why is he continuing to flirt?
Post Opinion