Start a conversation with the understanding that you came to talk to his behaviour that affects the job it's not private. You do not need to blame him, but be understanding for revised guidelines.
Start a conversation with him to understand that you talk to him about his behavior affects job. Not a private matter You do not want to blame him, but need to understand in order to find ways to improve.
Start a conversation with understanding to him that you talked to him about the impact behavior, tasks, not personal. You don't want to blame him, but want to understand to find ways to rectify.