This is where things get complicated. Usually, they'll flirt a lot with other people, paying less time to you. Sometimes, depending on how long ago the breakup/separation was, they'll try to get their mind on something/someone else. To hide the pain. Guys can be/act a lot like girls do in this category. Depends on the type of guy you're talking about though. For this question, it requires some details.
Don't waste your time hun, it seems like he's only messing you about. If he likes someone else, then he likes someone else. Surely you can do better than him anyway :) Good luck
Just all of the normal signs that someone likes you!
Leave him alone and back off. He likes someone else.
When he has a penis.
Have someone else do it for you.
tell them to get over you and date someone else.
It means he wants someone else but is flirting with you as a second resort if the person he likes doesnt like him back
Ask her straight out
He will try and make you jelous somehow, mabye dating someone else. Whatever you do dont go crawling back to him, let him come to you.
playing hard to get or someone else has been using the phone and sending you love notes
Ask her.
Move on