THIS IS MY THEORY/IDEA.

Recoil, the scene where he sees Locke with Ziva in the bar. :)

i think it happened gradually and he didn't even realize it until it just kinda hit him that he has loved her for a while.

does that make sense?

anyway i think there was a quote about it somewhere on the tiva quotes forum on the tiva spot.

i agree with crazy_frog222

i found the quote

"Well, it seems to me that the best relationships--the ones that last-- are frequently the ones that are rooted in friendship. You know, one day you look at the person and you see something more than you did the night before. Like a switch has been flicked somewhere. And the person who was just a friend is...suddenly the only person you can ever imagine yourself with."
- Dana Scully (The X-Files)

I agree Dannii, i think round about that time you noticed differences in the way Tony acted around her!

I think it was when she spilled her heat about her sister in front of the hotel, and it kept going from there, then Jeanne *errgggg* had to go and skrew it all up, and he didn't really have time to decide whether to tell her....until * the most idiotic, vile person who i'm glad is dead* --swept her off her feet--.......then he decided he needed her and went to somalia and now he's rebuilding her trust! but it just took a blow WHEN VANCE GOT IN THE WAY so, i guess it'll b a long time commingg! WOULDN'T THAT HAD BEEN SO CUTE THOUGH! HER FIRST DAY AS AN AMERICAN AND SHE ALREADY HAS THE LOVE OF EHR LIFE(: okay, i'm rambling! so i guess nope!

I agree with Katie, it definitely happened gradually.