Why would a guy hide stuff from a woman he's seeing but not in a relationship with?

I recently just found out that this guy has been playing games.First off, he was playing on my phone, prank calling my phone Calling my job and hanging up,so I basically told him, lets be together, he said no, Soo I told him to forget about me, and we should both move on, so after that he still continues to play games on my phone so a few days ago I called him to ask him to stop, he again denies it, though I know its him ,so anyway I changed my cell phone number and deleted my facebook page so he that I can move on with my life, so today a mutual friend goes to his facebook page and all I see are flirty comments that he made on other girls profiles that he had hid from me, when I was on his facebook list, then he unhides a mutual college friend event that he's going on in a few months whys did he do all of this, when we werent exclusive??