They've been married since the mid '80s, and show absolutely no signs of being unhappy.
that is probably means they are terribly unhappy.
l learned a few things from my parents on what makes a long marriage last:
1. repeatedly tell folks about how unhappy you are
2. repeatedly bring up old arguments and wounds from the past.
and most important
3. get good and drunk every night.
made for a long marriage in my parent's case although they have cut the alcohol out. but for 30 years the sauce was an integral part of their relationship.
Poll
