"Jane Doe" was the name that Trip Tucker gave to Malcolm Reed's potential future wife.
While discussing in 2152 whether having prior knowledge of the future was a good thing or not, Tucker asked Reed if he would want to read in some book the name of the woman he was going to marry; Reed didn't hesitate to reply in the affirmative, adding that it would save him the awkwardness of going out with anyone else.
Tucker continued the analogy: "Fine. So one day you meet Jane Doe. You go out a few times, and you pop the question. She says I do, and the two of you live happily ever after." Reed reiterated his approval of the idea, prompting Tucker to make his point: "Now, did you marry her for love, or because some book told you to?" As far as Reed was concerned, it didn't make any difference as long as they were happy. (ENT: "Future Tense")