Frasier: I expressed my distaste for the way I'd been treated, yes.
Niles: Frasier, she rejected you in the most debilitating way a man can be rejected. You've got to more than "sort of" tell her how that felt.
Frasier: Well, I can't just tell Diane how awful she made me feel now. It's a distant memory for her. I'd feel weak.
Niles: You have no reason to feel weak. You've moved on in your life, too. You have a new career, new wealth, new success. You simply need closure in this one area.
Frasier: You know, what you just said made a lot of sense.
Niles: You're going to get closure.
Frasier: No, that business about my success. I tuned you out after that. I'm going to invite Diane over for dinner tonight, and I'm really gonna flaunt my success, really rub her nose in it. That'll prove I'm not just some cast-aside that never got over her. Niles, I know it's not psychologically sound. But we're still human. We have to do what feels good sometimes, don't we?