Gamora... my sister. She was dead in my time. Our father killed her. I couldn't allow it to happen again. I thought maybe the other me could change too. But she wasn't ready. She hadn't gone through everything that I had. Still felt trapped and unable to be more than what our father made us.

[She's sad about it. That she hadn't been able to get through to that version of her, but she's also not surprised. She knew full well the struggle to change and the weight of Thanos' boot on her neck.]