Wedding Bell Blues (S05E13)

In the series' landmark 100th episode, Lorelai and Rory feel obligated to give Emily a bachelorette party on the night before Richard and Emily renew their marriage vows. At the ceremony the following day, Rory tells Logan (recurring guest star Matt Czuchry) she wants a relationship with him even though he's not ready to commit. Later, when Lorelai, Luke and Christopher (recurring guest star David Sutcliffe) discover Rory and Logan together, half-dressed, the shocking scene leads to an angry confrontation between Luke and Christopher. A furious Lorelai figures out that Emily invited Christopher in an attempt to destroy Lorelai's relationship with Luke. (Warner Bros. UK)