: I get that she's an amazing piece of hardware for him to have. But does that
: really explain why he would suddenly become emotionally unstable by losing
: her? Aren't the Spartans experts at working with limited supplies and
: improvise?

: This makes it sound sort of like he lost his favorite toy and no longer wants
: to play solider. Which just seems to conflict so heavily with his
: personality from the books & prior games.

"favorite toy"

They've heavily laid on that Chief and Cortana have an intimate relationship. I think favorite toy is doing a bit of a disservice but whatever. Chief has saved the galaxy, learned about the nature of humanity, and been zapped with some Forerunner secret stuff, that can change your perspective of what is important. And he's not the perfect soldier anymore either, he disobeyed a direct order from Del Rio, his superior officer. I think that should signal the change in Chief's character. I imagine the realization that the UNSC isn't always right and that he has a choice in the matter can lead him to aimlessness and confusion.