Chell is trying.
She is trying to help Wheatley away from There, she is trying to swallow the raging torrent of emotions that is clouding her judgement, but something is wrong and she knows it.
There is a difference between his trek and hers, and the difference is that when he makes it to the road- farther than she ever did- he falls to his knees and does not try to get up. Chell doesn't know why she didn't catch him, or why she doesn't immediately lug him back to his feet, but instead of doing either of these things she steps back and watches the aftermath.
Though he didn't land that way, Wheatley lays on his side, curled into a helpless ball. His hands and knees have scraped the pavement of the road, and the noises he produces at the sudden pain- human pain- might just be the most pathetic, heart wrenching thing Chell has ever heard.
He's hysterical.
"Look at this," He makes a botched attempt at sitting up, nearly toppling back over as he does so. Wheatley holds his palms up to her, practically shoves them in her face, and in the darkness Chell can barely make out the blood that's beginning to seep through his skin. "Look at-at what She did to me!" His voice is a terrified shuddering mess. "I don't want this ! I don't want- any of this! Take- Take me back! Make Her change me back! Please lady, please! I-I'll do anything! Anything you want! Just please, p-please-"
His voice gives out as his eyes meet hers.
She isn't angry or disgusted like he expects her to be. Her eyes hold no hatred, no resentment for his words or actions, past or present.
Instead they are full of empathy and pain, and he doesn't understand either one.
All he knows is that she went back There for him despite everything he did- he deserves Nothing- and yet he still has the nerve to ask her to go back again. And although they hold no malice it is written plainly in her eyes- let there be no mistake- she Will Not Return for Anything.
Wheatley droops back to the ground and sobs.
Chell doesn't say anything. There isn't anything to be said.
Despite the fact that it's well into the morning, despite how little she trusts him, despite what he has done to her, she gives him this.
She allows him to mourn.