How to interpret the phrase "a young couple is a companion in old age"?

I remember I once watched a TV series called "Halfway Husband and Wife", and I think the meaning of the phrase "young husband and wife are companions in old age" should be more than appropriate if we use the name of this TV series to illustrate it. I think that no matter whether our relationship is stable and harmonious after we were young, if we have not come to the end, we can only be regarded as a halfway couple at most. And only with the passage of time and the test, we went together to the seventy years old, which is called the real old dependence, which can be called the old partner, do you think so?

Take my friends around me, one of them has a friend their marriage can be said to be very happy at the beginning, I remember they were married in 2005, two years later that is, in 2007 they have their own children, the family can be said to be in the future in the days together beautiful, in the eyes of anyone they are a pair of enviable model couples.

However, last year that is, in 2018, the unfortunate thing happened, due to various reasons they divorced, it can be said that this result is out of many people's expectations, the other day when we gathered, my friend and I said that initially, they are really very happy, but with the continuation of this marriage, and found that each other from the character, the values of the real existence of many of the contradictions, over time, this kind of mutual understanding. The friction between each other is getting bigger and bigger over time, which eventually leads to the inability to continue to live together.

Through this incident I do not know whether we understand a truth: young couples can be said to be a mutual integration, mutual adaptation, mutual understanding of the process, only to be able to peacefully go through this long period of integration, each other to endure the young that may be the throbbing and impulsive, it is possible to be accompanied by their own old age when they are still the one who is still accompanied with you have been with you all your life, the other half, once a young couple. The other half, once a young couple, now the old partner.