Ted: Okay, why shouldn't I tell Robin?
Marshall: Because deep down some crazy part of you still thinks you're gonna wind up with her, and I agree.
Ted: Marshall.
Marshall: I'm sorry, I'm Team Tedward. Always have been, always will be. Now, listen. I want my best friend to be happy. And if Robin could mean happiness for you, then, dear God, why help her go after another man?
Ted: Because she might still be in love with him. To not tell her, to not give her that chance, it's... it's selfish.
Marshall: So be selfish.
Ted: I can't do that.
Marshall: Tell that to the onion rings we just "split."
Ted: [sighs] Robin is my friend.
Marshall: She's always been more than that and you know it. Now, as we speak, my wife is in a hotel room cheating on me... with herself. But I'm not leaving here until you promise not to say a word about this to Robin. Now repeat after me. "I..."
Ted: Well, I can do more at a time than "I."
Marshall: "I, Ted Mosby, promise to stop putting everyone else's interests ahead of my own, and for once in my life, do what's best for me."
Ted: I... Sorry, what was the rest of that?