My spouse and I had begun that process when he passed away suddenly at 56. Our kids were in their early twenties and we had married three weeks after college graduation. We were kids who married and grew up together. But we’d had so many life experiences together and so many challenges with moving it had made us a team.The second and third lines are my wife and myself. Our kids are 17, 15, and 13, so our life will be radically different five and a half years from now. We have been conscientiously having discussions about life after the kids are gone to avoid the fourth. I think we're going to be good, but it's easy to see how relationships can become frayed beyond repair, especially if people in those relationships aren't being vigilant in maintaining them.
If you can’t value your shared life and transition to being each other’s best friend it’s going to be tough.