It's hard to tell without seeing for myself whether you are describing stalking other dogs (which Ariel does all the time quite playfully) or more of a shying kind of behavior. I had a male who was very well- socialized who became fearful at about 6 months old. He had entered a fear period and had a mildly bad experience from which he never fully recovered. I neutered him, which did not seem to improve his behavior (which was in no way extreme), but I knew I would never want to breed such a sensitive dog.
He was a wonderful pet, but after some attempts to bring him around, I just accepted that he would always need some extra time to get used to strangers.
My advice: Don't neuter early due to this behavior and don't push him into situations that seem to cause a fearful response. Wait out the fear stage and then try those situations again later.