Looking back since the beginning of the Twilight movie, I am convinced that Rob and Kristen started falling in love during the making of the film. Maybe even before hand - after all Kristen has said in many interviews that she and Rob spent every night of preproduction at her dining room table but only the last two days were actually productive - so what were they doing all the other nights? I know she was supposed to be with Michael at that time and CH warned Rob that Kristen was still under 18 - but I don't believe she really was with Michael and even although we saw some pics of them together, Kristen never showed the feelings for him that she obviously has for Rob. Summit worked hard to keep Robsten apart and keep Michael around the set. But at Comic Con in July 2008 - look at the way Rob and Kris ignore everyone and talk to each other. By Comic Con 2009 Summit always placed another person between them whenever they could. Just look at the red carpet premiere for Twilight - Kristen is wearing the red/grey dress - their eyes give them away.
Sorry so long but I have many more examples. Please give your thoughts