If your boyfriend is acting that way he probably wants people to think he is better off than he is because he needs to feel important. He doesn't want people to know that he is struggling because that is embarrassing to him. If you are ashamed to be with him when he does those things ask yourself this : Is this something I want to gert used to ? Is this something I can live with for the rest of my life? If you answered no I suugest you find a new boyfriend or confront him about how he is making you feel.
is his kissing other girls or other guys?
no, Because your the boyfriend and he is an ex only.
he is feeling insecure and needs you to validate your feelings for him
if he loves her he would not care.
because you yourself are insecure
You either have low self-esteem or he has cheated on you and you don't trust him.
Probably insecurity, or he is telling you that he chose you and only you out of those girls...
It means he's insecure.
Because maybe he's insecure and needs to make sure that you dont still have feelings for your ex
It means he's probably insecure. Positive reinforcement helps to cure this, reward him when he's acting nice.
you're either insecure about your relationship or you suspect something and just want the evidence to bust him
It likely just means that he is wondering why you were attracted to him in the first place... maybe he's feeling insecure.