Dear Grandparenting: My son and daughter-in-law are married but will not act like it. They both run around. How much, I don’t know. That kind of information is between them and their maker.

Here’s what I do know: This has been going on for some time right in front of my three grandchildren. The poor things are lost in this crazy game. They don’t know what to expect from one day to the next, much less what stranger their mother and father might bring home. I am so ashamed that I raised a son to be like this.

All this cheating has not made anyone happier. The tension is so thick that it’s enough to suffocate you. I cannot begin to imagine what this is doing to my grandchildren.

My son is too far gone to help, but the grandchildren are another story. That’s where I can make a difference. I have toyed with the idea of taking in the grandchildren, if that’s even possible. Even if my son goes along with it, the grandchildren might turn thumbs down. They will soon be teenagers. What is your advice? Emily Owens, Cincinnati, Ohio

Dear Emily: Somewhere there must be children of an open marriage who are well-adjusted adults living happy lives in long-term relationships, except we don’t know any, and we know plenty who came of age during the late 1960s and ’70s, when free love and open marriages entered the conversation.

Stepping out of a marriage with children for affairs and hookups is akin to a mad scientist running too many like experiments simultaneously. You can’t control all the variables. Open marriage is an experiment. Children are, too, in a sense. You add the right ingredients like love, security and stability and hope for the best. You get one shot at doing it right.

But you can’t re-do your grandchildren when the experiment fails, and a marriage with two footloose partners opens a nasty can of worms that is ruinous for young children. They become marginalized or pawns in their parents’ shenanigans and might go looking for love in the wrong places.

Under the circumstances, we wouldn’t hesitate to take on the challenge of taking a more active grandparenting role. Instead of being ashamed, make yourself proud by restoring some sense of normalcy. Grandparents can indeed make all the difference.

GRAND REMARK OF THE WEEK

Sheila Foster, of Greencastle, Pennsylvania, reports that all seven grandchildren use the same magic words.

“They might live in different states and have different interests, but they all have one thing in common. They know the two magic words to get what they want: Please, Grandma.”