So many things. As we grow older we change our way of thinking, learn new things, and sometimes realize that you aren’t getting what you need out of your relationship anymore. My husband’s work took precedence over everything; even when he didn’t have to work. I was left alone most of the time. Even though we had children, when they grew up and left that didn’t improve anything. I have hobbies and he didn’t.
After so many years of trying to be the dutiful wife and keep things together, I realized that I couldn’t take any more and stay sane. His needs were more important than mine, and he really didn’t understand that.
Everyone’s situation is different, but to me the reason for falling out of love is lack of communication, lack of getting needs met, or just being taken for granted.