Not *so* great a leap. Especially considering that in this universe, he apparently wasn't such a colossal asshole to her that he was alone in the vehicle and trying to text at speed in a sportscar. Still just as arrogant, apparently.
The only problems I kinda had here is how it seemed like a prep course for the new Spider-Man, and that it really wasn't so much Strange's fault than it was the Ancient One for splitting his decision into two and trying to pit his clearly weaker half against an evil half with centuries worth of power acquisition behind him.
However, that bit of nitpickery is negated by both the fact that this Strange becomes aware of The Watcher's presence (who I will *not* assume is Uatu) and that Twilight Zone/Outer Limits type ending where he apparently is trapped forever in what is left of his universe to not only mourn the fact that he sealed its fate, but lost the love of his life twice.
Got major "It's not fair; I had time now!" vibes, except it was a vastly greater weight than self-pity.