I have a son who has a problem keeping people in his life. Problem with him is he is very arguementive. If someone is doing something one way, he always know's a better way. He wants to debate when a subject comes up, no matter what it is. Basically, he rubs people the wrong way.
What I have found out after many years is when he starts up I will change the subject, or when he has a better way to doing something I have done for years one way, I will just say "this way works for me".
I'm his mother, so I know I have to make concessions to get along, but others don't.