I'm happy he's happy but sometimes I can't feel just a little jealous.
Most Helpful Guy
In my book, it's a sign that you have yet to move on from him entirely; residual feelings.
Or, perhaps you are not satisfied completely with being a friend only to him or, and with the new person you are seeing.
Any of these reasons, coupled with the fact that he seems quite satisfied, could be the cause of your jealousy.
Most Helpful Girl
I'm very territorial and I know when I have deep history with someone, I do get jealous seeing them with someone else