Uh-oh. Was he a charmer? Is it possible you were blinded by him?
Let me put it this way. Narcissists always come first, always. Was he able to put your needs and the needs of your children ahead of his? If so, you're looking at MLC.
On the other hand, it's possible for people to possess narcissistic traits without being full-blown narcissists. They do have the potential to "give in" and become narcissists.
The answer to this question lies in his personality and ability to put others before himself over the years. If it was a sudden change, probably not. If it's gradually been building over time - you may have a bigger problem.