Most Helpful Guy
He doesn't know what he wants, he wants everything. If he wanted you exclusively then he had that, but it wasn't enough for him. Now that he's with this other girl it seems that she's not enough for him either, but that doesn't mean that you are. This guy just does what he wants and keeps everyone else right where he wants them. I don't see how any of that is good for you, or for his girlfriend. You both want a guy who knows what he wants and sticks to that.
Love is a two way street and is based on someone being worthy of love. This guy is not proving himself to be worthy of love.
Most Helpful Girl
Some guys do that