There was a long period in the early 90s when Nightwing was basically just in flux.
After his marriage to Starfire in New Titans #100 in 1993 was interrupted, he was sort of in limbo for a year, with a few guest appearances here and there.
And after he was completely written out of New Titans, he had a storyline filling in for Batman post-Knight's End and Zero Hour.
And then he was back to limbo for most of 1995 until finally he got a new costume and his first mini-series in late 1995.
It was still another year before he gained his own ongoing series in late 1996.
But that series was such a success that it lasted until just last week (and it was canceled not because it was not selling all right, but rather because Nightwing is most likely going to be taking over as Batman again).
However, a lot of the reasons for why Nightwing was in such a state of limbo state in the beginning of the 90s was because the original plans for the character fell through.
Originally, writer/artist Art Thibert was going to do a Nightwing mini-series that would run in 1992, concurrently with New Titans #93-99.
The series, co-written with Pamela Winesette, was about an alien invasion of Earth that led to Starfire being captured and Nightwing has to save her. The main point of the series was to establish Nightwing as an extremely competent hero, and to do so on the largest of scales - in front of the entire superhero community.
At the end of the series, Dick would have a newfound confidence and would ask Starfire to marry him, she'd accept, and this would all lead into New Titans #100, which would be the marriage of Nightwing and Starfire, which would be handled much like Donna Troy and Terry Long's marriage in Tales of the New Teen Titans #50.
Of course, the best-laid plans of mice and men often go awry, and in this instance, the editor who was driving the project, Jonathan Peterson, left DC for Image Comics in 1992. Thibert had already put off doing the mini-series for a time because of a commitment to Marvel for a Cable ongoing series, but he ended up dropping both series to ALSO go to Image Comics.
So the new editors instead had New Titans writer Marv Wolfman have a wedding ceremony go awry in New Titans #100 (the minister was murdered by a newly-evil Raven) and the character of Nightwing had a bit of a delay on his road to prominence.
Interestingly enough, Thibert had even done a poster to promote the series (that never happened) and DC published it in 1992's Titans Sell-Out Special #1. Here it is (click to enlarge)!
The scoop on this comes from Bill Walko's awesome Titans site, Titans Tower. Bill let the interview he did with Jonathan Peterson be reprinted in Glen Cadigan's great guide to the history of the Titans, the Titans Companion (click here to purchase a copy of the book from TwoMorrows Publishing).