The beautiful thing about going with "Butterflied" is that it's the moment WE are affirmed in our belief that Grissom is as crazy about Sara as she is about him.
For years he deflected her approaches or waved them off with a coy smile or a simple flirtatious word, but nothing stuck. When it came to the nitty gritty of initiating something more, he bucked every time. She approached him with an offer of something more, with the invitation to try something new in their relationship, and though he acknowledged something existed between them, he never defined it. He never gave it a name beyond a vague "this."
"Butterflied" is about revealing to the audience and to Grissom just how much Sara matters despite all his attemps to deny it within himself.
I remember, I was unspoiled when the episode aired. I was fresh into the series and had seen season 1 all the way through, and parts of 2 and 3. When "Butterflied" aired, I already knew that Sara had a thing for Grissom, but I was still searching for affirmation that he felt the same way.
After "Butterflied," there wasn't a doubt in my mind. When he approached that crime scene, when he saw the face of the victim and first registered what it reminded him of, you can see the mixed emotions flood across his face. From that moment on, any scene involving Grissom is attached to Sara, because that's all he can see.
When he walks outside, his eyes fixate on her. They lock, but before she can question his unusual gaze, he shifts his eyes to Brass, making her wonder if the moment was intentional, accidental, or all in her head.
Throughout the episode he keeps Sara out of the bathroom, away from the place where the woman actually died. The connection is already too real for him. He doesn't need her standing there, but it already has a hold on him. He sees her in his mind on the bed. He's flustered when she calls, and when she finally sees the victim and realizes what's going on, it hits her hard, too.
Season 4 Sara thought she was going to move on. She had tried asking Grissom out and it didn't work. Yet, here she was, face to face with her doppleganger, the face that sent Grissom into days without sleep, slaving to find out who killed the nurse, as if solving the mystery would somehow release him from the torture. Because, he feels tortured as though it were Sara on that floor, and for the first time in a long time, he's forced to deal with his own demons, and his feelings for the beautiful brunette in the office.
Those final moments, that final confession is one of the most beautiful moments on CSI, still. It's a man, broken and exhausted, worn out from the search, struggling to maintain his cool, and sitting there face to face with the murderer who might as well have gone after Sara as far as Grissom is concerned in this moment.
Grissom sees this man, this murderer, and realizes that he sadly has much in common with this man. They're both older men who fell for younger women, but where the doctor opened his heart and was destroyed by the woman's cold-hearted ease to move on, Grissom remains closed. He tries to keep his heart from opening because he doesn't want to be burned. He openly admits that his own fears keep him from being with the beautiful young person who offered him a new life. He couldn't do it. He was afraid. He let it go, and for the first time, we see that he has regret where Sara's concerned.... but the fear is too great.
And as he confesses just how much she means to him despite his efforts to shut her out, she's watching and listening, and realizing just how broken this man is, but remembering just how much she cares. It hurts to know that fear was all that held him back, but helps her understand the situation, and him, a little more.
At the end of the episode, there should be no question in most people's minds that Grissom learned a lot about himself and his own feelings towards Sara. He could love her. He really could, but he's holding back because he's afraid, so terribly afraid, of it being taken away from him, of it being fleeting. He worries that she'll tire of him and his eccentricities.
Of course, we all know otherwise, but there's something so beautiful about seeing a man so broken down and tortured, and yet the torture opens his heart up enough to pour out a truth for the world to hear, something long buried, too long.
It's just such a lovely parallel to the season finale, if you think about it. In "Butterflied" he was forced to face the reality that she might not be in his life forever. I mean, sure, she'd threatened to leave in the past, but he always found a way to keep her around. He hadn't thought of the prospect of losing her due to the whims of one who would strike her down and end her life.
Now, here we are at the end of Season 7. In Season 4 Grissom connected Sara with a dead nurse. In Season 5 he watched her be attacked by a mental patient while he froze. In Season 7, she was stolen away and left to die in the desert while he frantically shook the only woman who might hold the information to save the "only person [he] ever loved."
We've seen him deal with these fears before, and every time ("Butterflied," "Committed") he shuts down. He doesn't function properly. He moves on autopilot. If the season opens with him doing the same, it'd be beautiful continuity.
And... I have to stop writing, now.