I think anything other than cheating can be worked on.. you both have to be willing to put in the effort though. When you’re no longer willing to fight for your marriage or put forth effort, it may be time to separate.
My first husband was the definition of narcissist. He also thrived off of tearing me down and was gaslighting me for 5 years until I was so broken that I was no longer entertaining for him. Ironically he left me at that point and proceeded to fight me to be legally divorced because he didn't want to pay child support 🤦 because we had children together and our mediator for visitation rights was worn to the bone by this man, I had to endure him interfering in my life for 3 hours per day, every other day for 18 years.. he left me when our second born was 3 most old, it took 2.5 years to finalize a divorce.
I got tired of always being lied to cheated on and manipulated. I gave up hope and finally realized that I’m not who he wants to be with.
He lost feelings for me. First year of parenting. And he kept on telling lies how much he loves me till last month when he broke up with me. He is also struggling with depression, and so I put the blame on it.