Dear Amy: I am a father to four adult children and a stepson. All are married or have long-term partners, except for my youngest. I have been with my current girlfriend and her two teenagers for over five years.

I decided, when the first vaccine for COVID was nearing approval, to invite all my children and their spouses/partners on a seven-day cruise next year, all expenses paid.

My unattached youngest daughter asked if she could bring her best friend, and because I was paying for everyone else's partner, it seemed fair that she also could bring someone.

When my girlfriend found out about this, she was livid, insisting that the best friend (whom we had never met) was not a family member and should pay her own way.

My girlfriend is threatening not to go, nor will she allow her two children to accompany us. My girlfriend has never gotten along with my youngest very well, but she insists that her issue is entirely about who's family and who's not.

I am at a loss as how to proceed. I would feel terrible uninviting the best friend. My daughter might refuse to come. Other family members might drop out. On the other hand, all my children are adults, so my relationship with my girlfriend should be a priority for me, right?

Amy says: You are not married to your girlfriend, which means she's not family, either. Nor are her children. Plus, she isn't contributing money toward this generous trip, so why does she alone get to decide who falls into what category?

Because it is your dime, you get to choose how to spend it. You should tell your girlfriend that the offer of the trip is still on the table, and you hope that she and her children will accept it, but that the final decision is hers to make.

Knowing when to butt out

Dear Amy: Before my son got married, he and I were extremely close. So, after his marriage to a wonderful girl, my son still would ask my advice and then mention to his wife how I would do certain things.

A close friend pointed out to me how this probably bothered my daughter-in-law. The next time my son came to me for advice, I steered him in the direction of his intelligent, smart, amazing wife.

My relationship with my son and daughter-in-law is still strong, but their marriage became even stronger. Mothers-in-law need to know their place!

Amy says: It can be challenging to step aside and allow a new spouse to become a primary partner to a child you've raised. Your wisdom applies to all in-law parents — not only mothers.

Send Ask Amy questions via e-mail to Amy Dickinson at askamy@tribpub.com.