That's such an interesting observation about Grant's state. You're right in that he was worn down physically. Yet, he was also exhausted mentally as well. Constantly hanging onto that book, keeping the man he loved from seeing John's letter, it chewed into his soul. He had to turn it over.
Still, as you said, it took courage for Grant to do it. I maintain that Grant owes John a lot. That letter, and the "voice" that Troy hears both served to steady that roller-coaster-ride you spoke of. They made him prioritize Grant ... even in the moment Grant was trying to make Troy a priority.
The friends and their support definitely had an effect on both of our guys. Knowing if things go wrong, you can knock on a door, fall into waiting arms and cry ... well, that is a safety net of a sort.
Thanks for the great comments!