KIRK: “do you think we are in love in every universe?”
SPOCK: “…of course not. that would imply that we exist in every universe.”
KIRK: “okay, then– are we in love in every universe where we exist?”
SPOCK: “how do you define ‘we’? if a universe has entities that share all our DNA, does that count as us, for your purposes? Or must they also have at least some of our upbringing? How much difference in nurture would make them someone else? For that matter, how much difference in genetics?”
KIRK: “…I think if they aren’t in love with each other, they don’t count as you and me. i think that’s part of our definition.”
SPOCK: “…ah. Then you have reached your desired answer by tautology.”