When a guy dates his ex without telling his present girlfriend...

This is totally wrong. If it was a friendly date, why not tell his girlfriend about it? or maybe the present girlfriend can come with them.. Well, it's all about trust. It's not right to keep secrets from each other.

That's plain and simple cheating. Your friend should know better. I wonder how would your friend react if he finds out that his wife also dated her ex?

it is a crime in my opinion. when you are already in new relation, its not just right to date the ex. it seems that person is not able to get over the ex.its also cehating in his part.

That's wrong. If my boyfriend was doing that and I found out I would break-up with him. If a guy or girl isn't happy with the person they're with they should break up with them, rather than cheat on them and have them find out and get hurt.

To what I believe its merely and simply just wrong, I would suggest that guy to be in his girl-friend shoes, then perhaps he will realize how wrong he is..

This situation spell trouble. Just a matter of time before the present girl will know about it. No secrets can be keep a secret forever. I just wonder why the guy has still communication with his ex. It's odd...really odd. If a relationship is over and you are currently in a new relationship. Then you want to have a continous communication with the ex. You must confess it to the present girl. So that misunderstanding and jealousy can be avoided. But even if you will tell the girl about it. I don't think she will be reasonable enough to understand it. It's really a difficult situation. The best thing for the guy to do is to cut his ties with his ex and face his new life with out her.

I think if you feel like you have to hide it, then it's something that you yourself don't think is right. I would feel pretty betrayed if I was the current girlfriend and found out he had been doing that.