She would take no further chances, even if she did actually care for Mono (which I fully believe she did as she seems shaken after leaving the tower and throughout the game aids him when she could simply just leave.) Also she’s a child, so when she gets overemotional, she’s way more likely to act irrationally. We’ve seen that Six isn’t forgiving and seems pretty paranoid, or at the least mistrusting. Like I said, to her, she was betrayed first, so she got rid what she saw as a potential liability. The fact that she even turned around at all to catch him shows this, she even takes a long moment of hesitation to consider before dropping him. I don’t think she hates him (at least not fully), but definitely has very conflicted feelings about him. Obviously Mono had no malicious intent with this and only wanted to save his friend, but Six felt differently. She even tried to share her music box with him once she recognized him, to which he began destroying it, destroying her safe space (seemingly painfully too considering her screeches of pain.) With this perspective in mind, in her eyes at least, she was betrayed first. She was fixated on her one source of comfort by the tower and it provided a place where she was safe and content, protected from the outside world. Mono essentially stole Six from her safe space in the second game.
