Jenn knocks it out of the park with another AMAZING review. Here are my favorite parts:
You see, when Oliver looks at Felicity, he doesn't see his past or his present. He sees his future. He sees what could be. And that both exhilarates and terrifies him. Because that means he would do anything for her. Not just to keep her safe, though that is a part of it. He would literally move heaven and earth for that woman if she asked (a fact solidified in this episode).
And he knows, in that moment, that if she asked him to stay, he would have a very difficult time saying no.
if he kissed her then -- really kissed her -- when he was preparing to go off to battle, he would not be able to leave her. I have no doubt in my mind of that fact.
And in this absolutely beautiful moment by Stephen Amell, Oliver turns to face her, takes a deep breath and -- with tears in his eyes -- tells Felicity that he loves her. He actually and finally says the words "I love you" aloud to the blonde and that's when Felicity knows, I think, that he's not coming back. And really, when you think about it, this is the moment Oliver knows he's not coming back either. He wants his last words to Felicity to be "I love you" -- the thing she will remember about him for years after he's gone; the tenderness in his voice as she replays the moment over and over in her head. He wants her to remember that -- to remember HIM not as The Arrow. Not as a hero off to battle or a vigilante avenging a wrong. He wants her last memory of him to be of HIM -- Oliver Queen -- professing his love.
She knows that if she told him she loved him, he would never leave. Felicity Smoak bravely and boldly lets Oliver walk away knowing that she is one of the very last things on this earth that he is certain about.