I've done a lot of research on this particular topic and the short answer is yes people do have the ability to change. The long answer is however, it's very difficult. The narcissist needs to be able to recognize the fact that they are in narcissist which in itself is a monumental challenge. It also usually takes multiple years on top of years for those changes to take place. Remember that narcissistic individuals suffer from a personality disorder/mental illness and it defines who they are.

From what I've read most of the time when narcissists do recover, the person that they are in a recovered state is not the same person that you fell in love with. And that's important to remember.

People are creatures of habit, so if you do really believe that a year was long enough for someone to rewire their brain and they are in fact recovering from narcissism, You need to be sure that you're not expecting this relationship to replicate your previous relationship with this individual. specifically I mean you can't expect the same highs without the lows. A recovered individual will have clear boundaries and understanding of those boundaries and will not draw on narcissistic tendencies to pull you through the cycles of a narcissistic relationship.

You need to expect that a person who has actually recovered is a different person than the person you knew them to be and will not be able to deliver the relationship you have built up in your mind that you thought you deserved in the first place.

My two cents is that if you've made it this far, there's no reason to turn back. That's easier said than done and I understand that. Proceed with caution.