As we know, Jake and Cassie's relationship bit the dust. KA tells us the reason she had that happen is because relationships that grow during wartime sometimes desolve after the war.
My question is, when did Jake and Cassie's relationship really become strong? Besides the big kiss in book 26, I don't really see it getting much stronger than when Ax comments on them holding hands in book 8. They already had something going befoe the war started. They were already at the hand holding stage. They were already at the stage where they could look at each other, and tell what the other was feeling. They never seem to grow much beyond that, even after the kiss.
They never actually start dating, to my knowledge. I'm not sure if they even dance together much.
Rachel and Tobias, on the other hand, steadily develop a relationship, and have many moments between them. Dancing, eating together, and all that. The strength of their relationship really shows through when Tobias gives up life as a Human completely after her death.
It confuses me that KA would send the message about relationships growing strong in war, and dissolving during peace, when Jake and Cassie's relationship was the weaker of the two. It never develops into a storng steady relationship, as far as I can tell, beyond what was there from the beginning.
Rachel and Tobias' relationship was over, but only because she died. If she had lived, I doubt anyone would think they would split up after the war. Or does anyone think they might afterall?