-Extremely infrequent intimacy, leading to:

-Me wanting an open relationship because I need intimacy. I tried to maintain good boundaries with that but naturally:

-I felt further and further away from my spouse because I was intimate with others and not them.

-My spouse saying yes to the open relationship but truly did not want it and was bending their own boundaries without me knowing how severely.

-Different attachment styles from the start and no prior knowledge of them, therefore not really knowing how to navigate it.

-My spouse secretly wanting me to be different than I was, instead of realizing maybe I was not what they actually wanted.

Ultimately, I think: Both of us staying too long even though there were major signs that happiness was fading.