Natural end to a relationship vs changing the C line

I’ve been thinking of a divorce. I have no desire or attraction to my husband. I’ve never had a strong physical attraction to him, but it’s more pronounced now. I find myself thinking of all the things I want different in a relationship- open conversations, spontaneity, exchange of emotions, being passionate. We’ve never really had these things in our relationship and it never really bothered me. Now it does. I’ve been going through a growth process and thinking more about what I want in this life. Part of me recognizes that I can achieve all these things in my current marriage if I put forth the effort and start making the changes myself by initiating deep conversations, initiating something passionate and spontaneous, etc. But I don’t want to. I don’t want to put forth that work with my husband. After 15 years of being a certain way with someone, it is incredibly awkward and uncomfortable for the both of us to make these changes. I feel like I’ve outgrown my marriage. In learning how to say goodbye, I can see that my marriage served a purpose, I don’t regret this relationship, but I feel like it’s time to say goodbye to allow room for a new hello. How do you know the difference between a relationship that is truly outgrown and has served a purpose versus just trying to change the C line?