Though typically depicted as uncle and niece in the comics, it seems The CW's Supergirl will take the Martian Manhutner and Miss Martian relationship down a less familial path. According to executive producer Andrew Kreisberg, you'll soon be able to add J'onn J'onnz and M'gann M'orzz to the shows ever increasing number of romantic pairings.
"His relationship with M’gann is an important one over this next batch of episode. There is some really great stuff for David [Harewood] and Sharon [Leal] that we are really excited about. We love Sharon’s performance and we love seeing David and Sharon together, it’s some of our favorite stuff this season. We’ve been really lucky with our romantic pairings this season and we really think that J’onn and M’gann have a great storyline coming up.”
Since Miss Martian and J'onn aren't actually family, and the niece/uncle relationship has always been a cover story to hide M'gann's White Martian background, technically, this isn't THAT huge of a leap from comic book lore. This new dynamic should also give the criminally underused David Harewood more screen time.