When do you think Elena fell in love with Damon?

So the canon answer is 3x01 when he gave her back the necklace, but that has never sat right with me. It was certaintly a big moment for them, but for me, way back when, the shift came later.

At the earliest I think it happened in 3x05, when she's hurt and upset and he tells her he's never leaving her again.

And please no hate on this post, I don't even ship Delena anymore but I saw some discussion about this on another post and thought it would be interesting.