Why did he run? why is he avoiding me?

My ex and I broke up 2 weeks ago . We had a huge fight and agreed to end it . We have since talked and apologized to each other and just left it at that. Today I ran into him ( we go to the same college) and he seen me and ran! He left all of his personal belongings (coat,books, ipod) on the table and ran into the bathroom when he seen me. Why did he do this?