"It was the only way. I believe...there was a particular path with one outcome where we might win. Circumstances are somewhat different here."
As his fellow albeit freaked out human ran and kept running, Strange's answer was the only one that made sense, even if he couldn't fathom why. With so many fragments in his head, he wasn't sure what that path was and he was reluctant to admit that out loud. It might be pride or arrogance getting in the way, stemming from his prime universe counterpart. A counterpart that knew more about that 'endgame' than he did.
He could tell that this woman mourned for Gamora. It was her arrival and announcement that prompted Peter Quill to derail his own plan. Stephen didn't spent time with anyone on a truly personal level - he usually considered social visitors a distraction from his duties - but it spoke volumes that so many cared enough to mourn her passing.
"She's alive," he said, hoping it might put Nebula more at ease. "That other version of myself, my counterpart, split that universe into two paths. We're part of that second divergent path. Events are the same until a certain point. There's overlapping, meaning we're two of the most similar dimensions within the multiverse. We're in the one where Thanos' minions are still trying to gather the stones, and where Gamora is still alive."