..........dude, where were you when you were watching the series? How many episodes were Katejina and Chronicle together? All the way from when she was "captured" by him to the very end of the series. That's about 4/5 of the series. What the heck do you mean "not enough interaction"?
And buddy, it's clear that she was doing it for Chronicle the whole way. Her feelings for him set her on the path of a mobiel suit pilot. From there, she built an ego, and when Shakyi and Usso clashed with her ego, she snapped.
Anyway, you asked for an explanation, I gave you one. You said yourself you didn't understand how it happened, so how do you think you can correctly explain and refute explanations given by other people?
I'm calling it quits now.
I try to explain something to somebody who says he doesn't get it, then he pulls a 180 and starts saying I'm wrong when, again, he said himself he didn't get it.