Well I been guilty of this too - making girl that I dont actually like to feel great and then in fact having other girl in my heart.
I was thinking only girls doing this - finding another partner before ending relationship. But wow, guys do that too. It kinda sucks that relationships ends but your ex isnt looking for a new partner cause that person are already found and established contact while in relationship with you.
But hey things might not be as they looks like. He might as well had found out that he have a cancer and to not to make you suffer because of it he ended things and faked his relationship status on FB so it would be easier for you to move on.
Doubt kills more dreams than failure ever will