Happily married to a narcissist?

Only if the narcissist is working on improving themselves, as narcissistic traits and impulses are actually really difficult to “fix”. Otherwise narcissists will drain you and make you feel lesser, in my experience.

There's a 0% chance to have a happy marriage with a narcissist.

I do not believe so ... some can be civil for awhile but in the end they will always put themselves above everything else. ALWAYS.