i think the whole confession in Butterflied said the most about their relationship at that time, than any other moment, we want to interpret. therefore, time to get seriuos, folks. i'm gonna try to read into what he said in that episode and fit it to our SF theory.
It's sad, isn't it, doc? - Grissom finally realized that how he lives isn't making him happy.
Guys like us. Couple of middle-aged men who've allowed their work to consume their lives. - Another indication that he is not satisfied with his life.
The only time we ever touch other people is when we're wearing our latex gloves. - We see that Grissom actually admits of being human, admits that he also needs human contact.
We wake up one day and realize that for fifty years we haven't really lived at all. - Maybe an indication of a breakthrough in his thinking. If he had a chance now, he would change the direction his life is heading. Possibly, he regrets previous choices he made.
But then, all of a sudden we get a second chance. Somebody young and beautiful shows up. Somebody ... we could care about. - IMO the All of the sudden phrase excludes the possibility that something serious happened between him and Sara in SF.
She offers us a new life with her but we have a big decision to make, right? - I would interpret this part in a way that Sara knew he is attracted to her. She offers a new life, right? She wouldn't do it if she didn't have a CLUE about his feelings.
Because we have to risk everything we've worked for in order to have her. - Obvious reference to his job as a factor which made him to not act on his feelings and take a risk.
I couldn't do it ... but you did. - it means he just didn't do anything in LV. but in SF? well, all i can think of is that in SF they connected on a level, that they were both aware that they're attracted to each other, but nothing serious happened. it doesn't really matter how they got to this conclusion. i think Sara knew of his attraction to her, and possibly this knowledge made Grissom MORE sheepish than when talking to any other woman. for example, he liked LH, and he wasn't sheepish around her. well yeah, she could read him, but things she said about him weren't anything he actually indicated. he was more fascinated by how she got those conclusions right. with sara it was different. i think in SF he declared his attraction to her, so that on CSI she always knew it. and we all know that he doesn't like when people know what he really thinks deep inside. so when a woman knows that he's got feelings for her, he's just uncomfortable. that's why their interactions were so awkward in Snakes, PWF and many more.