Inevitable "What episode was this?" question..

Hi all! I'm trying to find the episode where Martin has a bit of a rant at Niles and Frasier. They've been mocking his current relationship (or desire to start one) and he snaps, pointing out that he was supposed to be with their mother for the rest of his life, but that didn't work out.

Thanks in advance.

UPDATE: Thank you all for your input, karma all round! I think what I've done is confused the scene you've all hit upon from Frasier S4E09 with a moment from an entirely different sitcom! Well the search continues! Thanks again..