Well, if you're from a different Earth than he is, then he might not even be the same person you know. He might have lived an entirely different life that led to the two of you never meeting.

[She's patient, not defensive, and prepared to draw diagrams if needed.]

But even if he isn't -- you have to see how that's unsettling, for someone to come along and say they know you, when you're already not predisposed to making close friends.