I felt just like you did. Loved my ex dearly. But at the end of the day the love wasn't enough. To boot our sex life wasn't up to par with what I needed, and craved.
I used the phrase I feel like I've exhausted trying to change myself and asking you to change.
At the end of the day he was crushed I was crushed but I picked myself up a few years later I hear he's doing well, and I'm with the man that I'd always thought I'd end up with.