So you have the following information:
FEMALE FIRST NAME
NAME OF COLLEGE
Detroit (Place where they once lived and may still live)
First of all, it would help if you just told us the first name, the nickname, and the name of the college. You may think that you’re preserving their privacy or something, but all you’re doing is making it harder for us to suggest any way of solving your problem. Telling us what they really are will give us ideas for how to help you.
Second, why don’t you tell us all the things that you’ve tried? You say that you’ve tried Facebook. Have you tried Googling on all of those items in various combinations? For instance, put “FEMALE FIRST NAME”, “MALE NICKNAME”, and “NAME OF COLLEGE” into the Google search engine. (Obviously, I mean to put the real names into it, not the fillers I have to use because you won’t tell us the real names.) If the names were Gwendolyn, Jazzy Z., and Siwash State, you might pull up a webpage with a mention of how Gwendolyn and Jazzy Z. Wifferstein, who graduated from Siwash State, moved recently to the Podunk metropolitan area. Similarly, put “FEMALE FIRST NAME”, “MALE NICKNAME”, and “Detroit” into Google. Try all the various combinations of the four things that you know.
Third, if you tell us the actual nickname, that may allow us to guess the real first or last name. If the nickname is Nicky, his first name may be Nicholas or Nicolas or Dominic, for instance. If his nickname is Wifferzie, his last name may be Wifferstein. (Yeah, these are artificial examples, but there’s no way to tell how useful the real one is until you tell us the nickname.)
Fourth, tell us anything else you remember about this couple. How old are they? What do they look like? Do you remember anything about what they were studying, which may tell us what they now do? Do you remember any interesting stories about them? Did they ever mention where they grew up?