A letter from a grandmother to her nieces, nephews and grandkids. When we realize that we won't be around forever and we look at our family, we realize that a long good life has taught us something...something that is worth sharing. The author asked 70 people/couples their thoughts on these 4 Marriage is... Marriage is not... Best Advice...Red Flags (things to consider before taking your vows). The average length of marriage from all these couples was over 38 years. Hopefully, these words from "marriage experts" will encourage our next generation to look carefully at marriage before they say "I do".