Relationships. We all have them. There are differences though. I 
don't have any problem at all with any of my family members walking up and hugging me.
 do have a problem with strangers or acquaintances doing the exact same thing. Why? I don't have the same relationship with them as I do with family members.

Think of this when a complete stranger or acquaintance wants to hug your dog or do something equally intrusive. 

Your dog forms relationships too.