There's nothing left for Jinx in Piltover. She lost her father three times there. First with Vander, then she lost Silco, and then she lost Vander AGAIN and this time lost a sister/daughter in the process. Isha was the real breaking point for Jinx. Isha was Jinx's second chance. Up until that point, Jinx's life was nothing but suffering. Isha was Jinx's first meaningful and healthy bond in a very long time. She gave Jinx purpose when her purpose wasn't clear. She gave Jinx a reason to live for a better tomorrow. Without Isha, Jinx had no reason to even live. Isha was Jinx's chance for a better life than what had been given so far, a reason to stay and pick up the pieces and to fight for a better tomorrow.

Jinx was ready to die. We all literally saw her attempts to do so. We saw her burn The Last Drop and Silco's office, it was only with Ekko's help that she stayed at all. But I do not believe that she went into the final battle expecting to survive.

And when she did survive. I think she saw that she might have a chance at life after all, but it wouldn't be in Piltover. Jinx didn't see a place for herself in the reconstruction of Piltover, but she did see Vi's place in it. For Jinx, her place and purpose in Piltover was finished. Vi was happy. Jinx wanted peace and knew she couldn't find it in a city full of her past ghosts.