Why does he seem to be explaining himself?

like this guy, but we broke up badly. I still have feelings for him, but I kinda keep my distance as I figure he probably has moved on. He is a very chatty, flirty kind of guy and lots of women like him. He makes a great friend too but I am very insecure so it didnt work out. Yesterday I saw him talking to this fab looking woman, but he seemed agitated when I came out & straight after walked towards me with his head down to say hello, when he could have avoided me. Today again I bump into him and this other younger woman & they were having an enthusiastic chat, but the minute he saw me he said hello loudly to me. Later I ped him and he said hello again but looked uncomfortabe again & went out of his way to tell me that he knew I couldnt join them because there was no space. (Where they were sitting has been filled up with rubbish bar one tiny spot). ~What I don't get is why he is acting like any of this has anything to do with me, like what he does is his business and we rarely talk and have very little to do with one another, even though we work together. In fact, he makes it his business most of the time to act like we were never friends even. Why the explainations?