One of my all-time favourite episodes of Seinfeld. Definitely one of the most well-written shows from Larry David. The way he deals with character development, a thing seldom seen on Seinfeld, is perfect for the show's tone. Jerry and George realize what we've all been thinking for 6 seasons of the show, that they act like children. They are in their 30's and are still single and have hardly any friends outside each other. "Are we going to be sitting here when we're 60, like two idiots?", asks Jerry. George responds, "we should be having dinner with out sons when we're 60!" So, Jerry exclaims he is going to make a change. George says so too, but it is easier to believe that George will go back on this and not Jerry. Jerry then breaks up with his girlfriend (because she eats her peas one at a time, hilarious), while George proposes to an old partner in Susan. The fact that George gets so upset with Jerry's actions shows how he values their friendship, in that he's only willing to mature as an individual if Jerry does too. This also brings forth the idea of "the pact" George believes was made, which is mentioned again from time to time in the seventh season.
The scene at the end, where we are shown George being forced to watch Mad About You in bed with his new fiance Susan instead of watching a Yankee game, is the most I've laughed at anything in an episode of Seinfeld. I laugh hysterically every time I see it, and it just gets funnier every time. The expression on George's face is unbelievable. It's at this moment where he fully realizes how much he is going to regret this decision. You can see in his face that he is thinking "What have I done?", and it is hilarious. No dialogue; just the happy, content face of Susan and the anguish of George, helped only by the frivolous theme music of Mad About You in the background. Possibly my all-time favourite Seinfeld scene.