First, is your dog neutered? A growing male puppy eventually hits adulthood and that's when the Alpha starts kicking in. If he isn't, I would suggest it. If he is, then maybe you are giving off vulnerability vibes and he feels he needs to protect you. For what ever reason, that seems to be an issue you will want to work on. I'd suggest a calm low voice. Don't tense up in preparation for an incident, stay as calm as if you know there won't be one. Don't let the dog out in front to greet anyone first. He should be at your side not leading the way. Make sure you really watch for any sign of escalation and a short sharp tug on the leash as a correction at the first sign. Snap him out of it and get his attention on you. If he likes treats, maybe have one in hand, just to waft past his nose to keep him focused on something besides the big bad intruder. Good luck!
