He is a guy with a good heart who is my childhood friend bec of me, he gets dumped by his gf of 6 months.?

He acts like a gentleman infront of others but whenever it is his friends, my friends and me are the only people. He always teases ONLY me. Then one day when I was going home from my sch, I saw him in the playground. Crying like he has lost everything. Its bec his gf dumped him and from that day he never smiles,talks,smirks or even looks at my way. His friends found that strange and start to ask me what is wrong but I promised him that I won't tell them about it. Finally, I found out what was the reason behind it, IT WAS ME. She didn't liked it that he acted that way only to him - like acting cutely,childlishly,open to me. I don't know what to do. I know I can't make them join again as she is going with a another guy but he is not over her. I don't like the way he acts. I know I thought he was annoying but he is the only friend who ever knew me for this long & understood me. He is my best GUY FRIEND. He have listen to my problems. I don't want to be his problem. I don't know what to do