TBBT's Worst Storyline Came Completely Out of Nowhere and Ruined Everything
Well, saying that it ruined everything might be an exaggeration, given that The Big Band Theory kept going on, and remained a huge hit, even after that storyline.
But it certainly left a sour taste in the audience’s mouths, and many believe it to be TBBT’s worst plot twist. We’re talking about that dumb story of Leonard cheating on Penny, which reared its ugly head in the finale of Season 8.
First of all, it existed only to stretch out the larger storyline of their romantic relationship some more after it had become stale. To recap, Leonard and Penny got engaged all the way back in the finale of Season 7.
While relationships don’t advance fast on long-running sitcoms, one could have reasonably expected the marriage to occur within the next season, probably by its finale.
Instead, Leonard drops the bombshell: as it happens, during his North Sea cruise, he kissed another girl, while drunk. Who said “the last-minute TV wedding drama”?
Yeah, TBBT employed this tired trope, and yeah, the revelation ruined Leonard and Penny’s first attempt at marriage, which occurred at the first episode of Season 9, so one season later they have to renew their wedding vows in yet another wedding episode.
Mission accomplished? Not from the viewpoint of fans, who were getting tired of the "will-they, won't-they" routine.
Furthermore, the cheating storyline itself is stupid and forced. In part, exactly because it existed merely to slow down Leonard and Penny’s predetermined path towards their marriage for another season, instead of doing anything radical with it. It was an accident, brought up out of nowhere, with just enough extenuating circumstances to spare Leonard real blame. It is arguable whether kissing another woman was in-character for Leonard, even with alcohol clouding his mind.
But keeping his infidelity secret for so long, when there was at least one earlier opportunity to confess, and then revealing it when he did was almost certainly out-of-character.
And finally, the whole story has no reason to exist at all. Penny could have gotten cold feet at the last moment for multiple different reasons. For example, even if the screenwriters wanted to completely avoid an impression of Penny being mean to Leonard, she could have remembered Leonard’s previous relationship with Pryia.