This scene has so much meaning. Stefan loves her so much. He smiles at Elena and when he sees her smiling at him, he smiles even more. He has such a caring look in his eyes. And then Elena sees it, and she backs off. She knows he still loves her, but she doesn’t want him to feel this way, she doesn’t want him to be hurt by her decision.
There is no maybe that is EXACTLY what influenced her decision. She doesn’t feel she deserves that love and she’s seen him happy without her, she doesn’t want to hold him back, that’s what she believes. I know it, that’s why there was never any talk between her and Stefan. Hell notice how she never knew Stefan was planning to leave town. If she knew, Damon wouldn’t have stood a chance because she wouldn’t be able to walk away from Stefan. Her facial expressions here tell me she loves him, not that she feels guilty he loves her. She feels guilty because she doesn’t deserve him any longer, to her he deserves better than her even if he is smiling at her. She doesn’t want him to be hurt by her anymore, THAT is what I get from this scene and what I’ve gotten from it every single time I’ve watched it.
→ Stefan and Elena + beds