Remember when Damon compelled Jeremy in S01? He was said that Vicki’s leaving is for the best, but he still felt something bad about it, empty, because he loved Vicki and than she died, he felt that but couldn’t understand why.
And now i re-watched 2x08 and understood something. Damon compelled Elena forget about his confession. But he couldn’t take away her feelings that she started to feel about it. I’m sure she did, you can see it on her face. AND, didn’t you notice that after 2x08 she started treating him much better, he became her friend again. She started to feel something for him even if she couldn’t understand why. I think it was the beginning for Elena to feel something for Damon not just like for friend. That’s my opinion. (sorry for bad english)