When you finally realize you don't want the same things!
There is no amount of "work" or "communication" that can overcome being with someone who simply does NOT want what you want. Compatibility trumps compromise.
Like attracts like and opposites attract divorce attorneys!
There are only two ways to experience joy and peace of mind in relationships. We either get what we want or we learn to be happy with what we have. Accept them (as is) or move on.
The choice is up to us.