My 25-year-old daughter, A, and her husband, B, revealed to us that she has a romantic and sexual relationship with their mutual best friend, C. Not an affair or a three-way, more of a second-tier husband. I see this as a doomed experiment, likely the result of immaturity, a poor choice on A and B’s part to marry, and a lot of magical thinking. One day I blurted out that I didn’t want to hear about C anymore; I am more comfortable pretending that C is just a friend of theirs and, as such, doesn’t need to be included in visits, family gatherings, or reports on A’s life. A is sad and tearful that she must keep her second great love in the shadows. I am sad that I’ve put this barrier between us. Any suggestions for how I can make this better? ANONYMOUS / Bedford

Thank you for asking me what you can do, instead of asking how you can change your daughter. You’re already ahead of most of the people who write to me, and I suspect you and A are going to be all right in the long run.

If you’re not familiar with the term, your daughter and her husband are what is known as “polyamorists.’’

These are people who donít feel that monogamous relationships can satisfy all of their intimacy needs. Maybe learning a little bit more about polyamory will help you feel more comfortable -- the Wikipedia entry on the topic is very helpful, if a bit overwritten. (Polyamorists undoubtedly contributed to the entry; they tend as a group to like wikis and open-source code, for reasons that are obvious when you think about it.) What your daughter and her husband are doing is definitely an experiment, but not necessarily a doomed one; many poly relationships last for years, and there are lots of communities online and off to help polyamorists learn the communication and logistical skills they need.

So, Dad, if your daughter is committed to this lifestyle, ask her to start using those skills with you. Polyamory is a new and disturbing concept to many people, and maybe you feel you ’even quite know your daughter anymore. Approach your daughter, alone, and start some conversations. Polyamorists know that relationships are always in a state of change and that all relationships need structures and boundaries that must be negotiated. Point that out to her! It will show her that you are open to learning about the way she lives, while at the same time putting some responsibility on her to honor your feelings and beliefs and not expect you to make an overnight 180 and invite C to carve the turkey at Thanksgiving.

Last night my husband and I went to a restaurant where we’re regulars. No sooner did we order than a woman and her 2-year-old were seated next to us. The girl started squealing loudly, banging her knife on the table, and acting like a baby who is just not ready for a fairly expensive restaurant experience. The mother sipped her wine and did nothing. In frustration, we grabbed our plates and drinks and moved to the bar. What should we have done? ANONYMOUS / Boston

Go to the headwaiter, host or hostess, or manager and ask to be reseated. It’s their responsibility to make sure that your dining experience is pleasant and that everyone in the restaurant -- toddlers, people with vehement opinions, BlackBerry addicts -- behave themselves appropriately. If you are a regular customer, I’m sure the restaurant’s management likely would have bent over backward to ensure that you were taken care of, even if the staff had to pack your meal to go and comp your drinks. Shopping local and getting to know your merchants isn’t just eco-friendly and good for the community’s economy, it’s an excellent way to ensure good customer service.

Miss Conduct is Robin Abrahams, a Cambridge-based writer with a PhD in psychology. Got a question or comment? Write to missconduct@globe.com. BLOG Read more of Miss Conductís wit and wisdom at boston.com/missconduct. CHAT Get advice live every first and third Wednesday, noon to 1 p.m., at boston.com.

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