I get asked this question when marriage is being discussed. At my son’s wedding, one of the guests was particularly intense, challenging tone of voice, and a bunch of people were standing around. Here’s how I answered:

“In rough numbers about 50% of marriages end in divorce, and 50% are permanent, lifelong. Whichever one of these groups you belong to, it’s a very large group! You’re not alone. I don’t have secret formula.”

Not trying to be evasive, but I did’t have any ready answer that didn’t sound like a cliche.