In the Vampire Diaries pilot, Elena and Stefan met and instantly fell in love, but their romance faced endless obstacles, including Elena's burgeoning attraction for the elder Salvatore. During the season 4 finale, Elena broke Stefan's heart by declaring her love for Damon. Just a little over a month before the season 6 finale, Dobrev announced on Dobrev played all five Petrova doppelgangers.) Stefan injected his brother with the Cure and sacrificed himself to save Mystic Falls and everyone he loved, and Damon got mortality and the girl.
In an interview with EW, Plec revealed she and Williamson had decided how to end the series during season 2. Damon and Stefan would sacrifice themselves for Elena and reside on the Other Side watching Elena live her mortal life, possibly with her childhood sweetheart, Matt Donovan. Plec hoped to reignite the Elena-Damon-Stefan love triangle, figuring out a way for the bittersweet friendship between Elena and Stefan to evolve into something more. Plec felt Dobrev's exit "sealed the romantic contract" between Damon and Elena. Plec told EW:
"In that moment, to me, the show ceased to be about a love triangle and became a show about the power of these brothers and their love for each other. And so there was no way in hell I was killing both of them and leaving neither of them with the happy ending. It just was never going to happen.”
It's certainly difficult to imagine how the show's creators could have clung steadfastly to Elena - who was adamant about people not sacrificing themselves for her - losing the two greatest loves of her life without severe audience backlash.
The Vampire Diaries season 7 focused heavily on Damon trying to be a good friend and brother in Elena's absence. Season 8 had both Salvatore brothers facing the repercussions of their violent pasts by introducing the character of Cade, aka "the Devil." The themes of retribution, redemption, and forgiveness were the final season's driving forces. The Vampire Diaries strayed far from its roots in the two seasons following Nina Dobrev's departure. Stefan and Caroline Forbes fell in love, but their romance lacked the ion and angst that Stefan had with Elena. If Elena had remained in the picture, the much-beloved Caroline-Klaus Mikaelson pairing might have gained more traction despite the character getting a spin-off set in New Orleans.
Even though Damon lives on thanks to Legacies' Easter eggs.