Sinon seems to have gone missing until Kirito finds her training by herself. She's been pushing herself so hard lately, and after Kirito tries talking to her about it, she runs off and nearly gets herself killed before Kirito finds her just in time to protect and save her.

Both are pretty shaken up, but Sinon has it the worst, causing her to break down into the very arms of the man she's fallen for. It's a very sweet and fluffy moment, and while Sinon still says this is something she needs to solve for herself, Kirito's proven he was serious when he said he'd protect her.

Though realistically, I've trained Sinon to a point where she could solo the rest of the game if she wanted, story aside lol.