Is this considered cheating?

There is this guy that I am hanging out with, we are not an official couple and we never talked about being a couple, I just sometimes hint that I want to be boyfriend and girlfriend. Yesterday I found out that a couple of months ago he was still hanging around and playing around with his ex. I felt pretty hurt and betrayed about this! I was just wondering is this considered cheating since we are not a couple and had no "dibs" on each other.