Raising children is one of the most difficult and rewarding accomplishments that any parents can make. While many parents do stay together until their kids have left home, the dynamic can change considerably when going from working and raising children to becoming retired and having an empty nest. This is why so many married couples consider divorce around this time.
This shift does not necessarily mean that couples need to divorce; some marriages just need time in order to adjust. Marriage becomes a choice rather than a commitment to raise children together, and it may take some time to reconnect as people as well as spending time to reconnect with yourself.