This episode is a really good episode yet really quite sad. Not only is Diane leaving for Europe with Frasier but this was Nicholas Colasanto's last appearance as Coach (apart from one outtake in Rescue Me), who sadly died of heart failure.
So Frasier asks Diane to go to Europe with him for six months and she says yes. Now, however much I like Frasier, I was *screaming* at my tv, telling Diane not to go because she belongs with Sam, but she does go, and Sam dutifully throws her a going away party.
At the end of the going away party, when the bar is empty, Sam and Diane hug and find it hard to separate themselves, especially after all they had been through together. Finally, they break apart and Diane starts to walk away before running to Sam and passionately kissing him (I should hope so too). They start to leave the bar together but Diane says something which Sam misinterprets, making Diane decide that sleeping with Sam that night would be wrong and goes to Europe with Frasier.
That scene is so Sam and Diane because they and every else knows that they belong together but things just don't go right. The hug is so funny yet so sad because Diane is leaving (Just like she did at the end of season two and like she would do at the end of season 5)