WHEN YOUR AHEAD DON"T REFUSE TO FIGHT!
I litterally just lost a game where an ADC refused to group and push objectives when we were ahead, we then lost 4 teamfights because she wasn't there and it made us throw. Please PLEASE if your ahead don't refuse to fight just because YOUR not ahead, if the team as a whole is doing better than the enemy team just fucking group, push down tower's extend your lead. Just because your not fed doesn't mean you can't help and that someone else can't carry for you.
Goddamned it i'v had WAY to many games where this has happened JUST FUCKING GROUP!