Q: My son and daughter-in-law have been separated for a year. They have shared custody of their 4-year-old son. My son was very unhappy until he met someone else. Daughter-in-law did not handle the breakup well. There were lots of threats, accusations, and harassment by phone, text and e-mail. My son will barely talk to her. They minimally co-parent. Son came up with a nickname for the child to call his girlfriend but I have heard the child and my son refer to her as Mommy. When I spoke to my son about this, he said the child did it spontaneously, and that his girlfriend is a better mom to his son than his real mom. Although she seems very nice, she's not a better mom, they just have different parenting styles. Am I wrong? What's good ex-etiquette?

A: No, you are not wrong. You are absolutely right ­— and so was your son by making up a nickname for his girlfriend. Where he went wrong was when he let his personal animosity for the mother cloud his good judgment. Never compare a biological parent and a new partner. A new partner is simply a third voice that supports the biological parent's parenting. If they love the child, that's a bonus.

How would Dad feel if the shoe were on the other foot? If this happens again, the best plan is for Dad to gently correct his son, even if it is initiated spontaneously.

That said, I don't know the true history, but your e-mail makes it sound like your son just moved on when he found someone he liked better. I'm not surprised his wife acted as you described. Threats and harassment are inappropriate, but few would meet the news of their partner seeing someone else with calm acceptance. But, all that is no excuse. Their baby didn't ask for any of this and it's his welfare that comes first.

Sometimes angry divorced parents ace out the other biological parent in favor of their new love. They do things like call the biological parent by their first name and the new girlfriend or boyfriend Mom or Dad. It's emotionally and psychologically detrimental to their children. That behavior puts a child in the middle and asks him to weigh his allegiance to either parent.

So, it's time to wise up, stop being selfish no matter what went on in the marriage, and make decisions with the child in mind. That's good ex-etiquette.

Jann Blackstone is the founder of www.bonusfamilies.com.