How do you move forward in life and move on from the relationship if they refuse to ever detach?
The detachment and moving forward is what you do - because this is about you. Always has been, always will be. Your happiness start and ends with you. You can live your life... . move on, do other tings and detach. If they don't... . well... . they just make things a little difficult, but... . that's on them.
It took me forever to figure that part out. Once I did and finally detached, things got so much easier in my head and heart.