Just like that, another Vampire Diaries couple bites the dust. Caroline dumped Stefan on The Vampire Diaries in "The Simple Intimacy of the Near Touch," and he definitely deserved it. Stefan and Damon brought their murderous ways back to Mystic Falls just in time for the Miss Mystic Falls pageant, and while Damon focused his trip on trying to sever Sybil's control over him, Stefan decided to be more self-destructive. At the end of the day, Stefan's ripper ways effectively ruined his relationship, and the Steroline engagement is now officially over.
From the moment Stefan stepped into the Miss Mystic Falls event, Caroline knew his humanity was off. What she didn't know was that he had gone full ripper. Yes, Stefan has officially gone off the deep end, and he's desperate for Damon to do the same. So desperate, in fact, that he aligned himself with Sybil and hatched a secret plan for Sybil to siren all the girls competing in the pageant into voluntarily standing by as Stefan turns them into vampires. Luckily, he only got to one before Caroline — ever the boss — threw a piece of wood straight into his heart, temporarily killing him and giving her time to get all the girls home safe.
By the time Stefan broke up, Caroline was fed up. She told him that from now on, they do this her way. And that means serving out this year with Cade only killing "murderers and drunk drivers." And that's when Stefan dropped a bomb: his deal isn't for a year, it's for however long he wants to keep going. And, right now, as a ripper, he likes what he's doing, and he doesn't want to stop — not even for her. Caroline responded by throwing him back his engagement ring. Until he figures out that he wants real happiness, the kind he can only get by turning his humanity back on, they're done.
RIP Steroline, you were loved.