As the years go by, the reasons for getting married, rather than cohabiting, are not the same as for younger couples. When you are young, getting married to the person you love usually seems the obvious way to make a commitment to the relationship. Your life seems bound up in the other person's. You want to be in each other's company as much as possible, to be there for each other at the end of the working day. You want to have children and build a family unit that will take forward the heritage of both of your families, and of the life you forge together.
Many older people have already had children in an earlier marriage. Even if they haven't, they may believe they are now too old, or they may be reluctant to start a family in their later years. Some people think it unfair on the children to land them with elderly parents who won't have the inclination or energy to join them in play and other activities for youngsters.
So why bother to get married? You can still be together as much as you want without the marriage license. In western countries, it's no longer frowned on by respectable people as it once was. But many couples still do it. If you ask a number of them for their reasons, they're likely to come up with quite a variety of advantages for them.
The first, and still probably the most important, could be that of conforming to their religious beliefs or the moral standards they have set for themselves. Older people are more likely to have been brought up at a time when unmarried couples were considered to be "living in sin". They may be part of a community or congregation of like-minded people that they want to keep in their circle of friends. It can be difficult to change the way you have been thinking all your life just because you have met your soul-mate.
Sometimes a couple has been cohabiting for many years and decides to marry simply to ensure the financial security of one party after the other dies. Pension plans that include a percentage for a spouse after death often only apply if the couple are married at the time that the pension is claimed. A will leaving part of your estate to your "other half" can be contested by family members, which is not easy for the survivor to fight at a time when he or she is grieving and vulnerable. If you are a husband or wife of the deceased, your rights are much clearer.
Couples have sometimes decided on a wedding to raise the status of one of the partners in the eyes of the other's family. If you don't have a marriage certificate, people can fail to recognize your commitment to each other, no matter how long you have been together.
Some couples simply say that as they reach retirement age, they have time to organize it. Or that they've finally got around to it and it's about time. On the other hand, it can be a lovely way to celebrate the fact that their relationship has lasted through the years.
Almost all partners who have been together for several years think that getting married won't make a difference to their lives. Afterwards, they've been known to say that somehow it feels different, or it feels right - an un-looked for advantage to marrying later in life.
And whatever their reasons, there is something very moving about seeing a mature couple tying the knot. They've recognized that, after all the different paths they've taken through their lives, they've finally found the place where they each belong. Side by side, to the end.