How did it not spot his narcissism?

[JessicaGerbil]

Recently divorced. Obviously no diagnosis but on the basis of his behaviour over the last 3 years in particular I strongly suspect he is a narcissist.

We were together over 10 years, how could I not have realised sooner? Could he have hidden it for that long? He seems like a completely different person now…

Without any more detail about the person or incidents etc etc it's very difficult to say.
But you say that you are recently divorced..so..does it really matter ? You are free to move on now ....

Yes, sometimes the nice features of a person are merely a free introductory offer and once they settle into a relationship and get complacent, the full horror of the situation reveals itself. Some people just don't have the software installed to be nice to anyone else long term. You can call it narcissism (but often they don't like themselves much either) but sometimes it seems to be part of a more general pattern of human frailty and uselessness.