When Jenna and Jeremy die in the battle with Klaus, Elena grieves for months. Neither Stefan nor Damon can console her, and they've both tried. So have Caroline and Bonnie and Tyler and Matt, and the rest of Mystic Falls, for that matter.
She's eighteen and legally an adult, so she doesn't need a guardian. She gets the Gilbert house—what's left of it since Klaus—and doesn't leave for any reason.
Caroline comes by to make sure she looks presentable at all times, and Stefan brings food for the kitchen on his visits. Damon constantly brings flowers and chocolates and other gifts to cheer her up, but none of it works.
Bonnie is grieving as well and doesn't bring anything but a strange kind of comfort in their shared misery; but still, Elena doesn't speak.
Then John shows up and all the sadness gives way to anger, and as soon as the front door closes behind him, Elena's pounding at his chest, tears streaming down her face as she yells incoherently at him.
He allows her to do this until finally she runs out of strength and falls against him. He holds her close and tries to be strong for her because that's what she needs right now. Someone to blame and someone to be strong for her—to take what she cannot bear and give her the strength to go on.
She cries against his chest and he breathes against her hair and later, Elena falls asleep in her father's arms for the first time, and John hates that them being the last to Gilberts in the world has caused them to become a family.