To be fair, he wasn't expecting John to start yelling or insulting him, he's too proper and polite for that. Other than that, though, he doesn't know what to expect, and when John stops in his tracks, sudden enough that it takes Jim a couple steps to realize that the man's no longer walking alongside him, is enough to nearly make his heart stop.

He turns around, taking a step closer to the other man, then stops again, finding it hard to take in even the slowest of breaths. His heart sinks in his chest, able to tell that John is upset-- he's just not realizing what John really is upset about.

"I did," he nods, fingers curling in, stopping himself from reaching out. "I'm... sorry, John, I know it wasn't my place. You have every right to be mad at me, but I still hope you'll forgive me."