Possible...but split seemed 'amicable'. Trump wasn't derogatory about him, which I suspect he might have been in a scenario like that. Trump's statements on what happened ring true to me...lots of policy disagreements, The 'Libya' issue, and apparently others in the cabinet wanted him gone, and major disagreements over Venezuela. It probably became obvious a change needed to be made. Yep. Firing without firing...ie, that's what asking for someone's resignation is. Which I also think goes against your scenario above...if it were some spur of the moment thing driven by an insult, it would have been an outright firing, don't you think? In that scenario, would Trump let Bolton save face? I don't think so.
It didn't seem amicable to me. In an amicable parting, his termination would be future-dated. They wouldn't spar over who dumped who, Bolton would have some excuse, 'to spend more time with his family' or whatever, instead of all the resentments Trump has built up about how other countries don't want to work with him and he's fighting with people in the Admin. And the timing was bad also, right after the Taliban talks were canceled. If it was just different visions, I'd think you'd wait a few more days. Anyway, I don't suppose any of it matters. Gotta give credit to Trump on this -- he doesn't get led around by the nose by his advisors. Bolton might have generated some ideas for him, but Trump's choices in national security were his own.