I am learning this as I am going through a break up myself...
I really think alot of it has to do with his personality and how open and open he is in general about feelings etc..
AT the moment my ex is behaving like he hates my guts he is treating me like I am a piece of poo you wouldn't spit on 'pardon the language' but he is very angry and this only shows how hurt he is.
We had been having troubles a while before we split up and I started seeing someone else when we actually ended it formally,I felt ready to move on maybe in hast maybe a bit of a rebound thing but I had come to terms with the fact it ended long ago and wouldn't work so I moved on and he found out and doesnt like it so much..
Once he found out I was seeing someone via another person he went out and found a new girlfriend within a week and has been trying to rub it in my face saying what an amazing person she is etc...
Really the more a man tries to hurt you the more hurt they are..
If he is acting cold and ignoring you he may well be recovering emotionally.
I really think its a vast world of emotions and personalitys involved with men so you cant really pinpoint why exactly they act the way they do.. Men just don't cope as well to stress as woman they either act like they don't care or they try to deny they are hurting and will hurt you and others in the process..
The only thing you can do in these situations is move on-don't contact'as hard as that is' ...You owe it to yourself to be happy.
As much as I have moved on and seeing someone it hurts my ex is treating me so coldly and detached after we shared 5 years together and have 2 small children..
I guess time is the healer of all wounds..
Good luck, just Google what you want to know and try seek as many answers as you can to gain insight into your question this has helped me..
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