I don't understand the behavior of my ex-boyfriend - please help

Hello, would like your opinion on the behavior of my ex. I broke up with him 4 months ago because he was not so much into me anymore, which he confirmed in saying that he was not sure about us as we were very different and I wanted more from the relationship than him. We remained in contact since then, mostly by email and chat, and friendly with each other but never talked about the break up again. Recently we have been meeting in group of friends together, and things were relatively ok, but his behavior is confusing me. He does not look at me in the eyes, is sometimes very cold with me, and never suggest that we go out together (the two of us). However, he is also usually attentive towards me, frequently mentions your past together and my friends said that he is looking at me when I don't look at him. I have the feeling that he is still attracted to me but would not act on it. When we talk together, we talk as very good friends. What do you think is going on here? And how could I get him back? Many thanks.

Why not come clean with him and just tell him how you feel then take it from there.

Yep, it sounds like a good idea. But wanted to have the opinion of guys first on why he was acting like that?

Because he quite possibly could be just as confused as you. Agree with Smackie, just ask him. Tell him you feel like you need to talk about how things ended.

I think talk to him it isn't a good idea. When you two broke up he agreed with the break up and if he anted to get back together he would try.
You broke up with him, but the true is that he ended the relationship, you just broke up with him because he wasn't into the relationship, if he was into the relationship you two would be together.
So he is the one who didn't want this relationship and he would certainly tell you if he changed his mind and wanted to try again.
It seem like you still have feelings for him, you probably didn't let it go your feeling completaly and that's why it's not a good idea to be friends with your ex with you still have feelings for him, you will read too much in every thing he does. You will see things where there aren't thnings because you still love him and have hope you will get back together.

I talked to him and he just wants to be friends... At least it is clear now... thanks.

Wants to be friends = not interested in you any more. Find somebody new.

This doesn't sound promising. It sounds like he might not be interested. I think you should tell him how you feel, and if he doesn't feel the same you should move on. Don't read into all the signs he is giving you. They seem inconsistent and not really conclusive to how he actually feels