They were all each other needed. Their relationship was toxic for awhile, but after an incident, Bonnie decided to turn her life around but Stefan took a little more time to change. He leans on her for support, for love, through his anger and pain and she's glad to be there for him. But he's hiding a secret and once that secret comes to light, it's like the world turned upside down and they have to fight harder than ever leading him to do whatever it takes to get her back.