You should respect other people's friendships.
Alan is friends with Doug who joined the basketball team and is now friends with the basketball players.
Alan wants to talk to Doug about being friends with the basketball players.
Alan will tell Doug it's cool that he made the team, and he's hanging out with all the players.
Alan tells Doug that being friends with the basketball players is taking away from their friendship.
Doug will think Alan is a chill guy and will introduce him to the players.
Doug will think Alan is being jealous and unreasonable.