Q: My husband and I hang around with five other couples. We all have kids and do a lot of kid-centered activities together. I have decided to throw a BBQ for Father's Day — the guys can grill to their hearts' content and the kids can swim.

However, one of the couples are splitting up. It upsets us all, but also presents a problem: My husband wants to invite his friend, but we can't invite his ex because they are not talking. She's my best friend and I know she will be upset if she is not included. What is good ex-etiquette?

A: This is the primary difficulty when taking sides after a breakup. You get stuck trying to figure out which side to be on. If you pick one, you betray the other. Not only that, but no matter how close you are as friends, you don't know what goes on behind closed doors. You may think you know the reason for the breakup, but they may not be coming clean. Meanwhile you're fighting with your partner over their issues and you may not really know what their issues are.

The fact that one side is your husband's friend and the other is your best friend presents yet another kind of allegiance question. I'm sure you will want to be your BFF's sounding board as well as your husband possibly wanting to lend an ear to his friend. How much of those conversations will be shared with you or your husband, which should be where your true allegiance should lie? Taking sides can open the proverbial can of worms.

The answer is to be honest and straightforward. That means make your boundaries very clear. Let everyone know exactly how you feel —or choose to keep your opinion to yourself — but don't play both sides against the middle. I've seen couples lose sight of each other in the name of supporting a friend. If you are not careful, this sort of situation can cause a serious rift between you and your husband.

For the record, all things equal — there hasn't been domestic violence, abuse, alcohol, drug or untreated mental health concerns, etc. — I always suggest you invite both sides when facing situations like this. Inform both of them that the other side has been invited and allow them to make up their mind if they want to attend — with the caveat that if they do both come, they act like adults.

If they can't remain civil, the host reserves the right to ask them to leave. If either calls you on that approach, stand your ground, particularly if you love them both and wish to continue your friendship with both of them once the dust settles. Bottom line, this is their problem. Don't make it yours.

Finally, it's Father's Day, a day to acknowledge the love and respect between a father and his children. Don't let all the breakup drama interfere with what the day is really all about.

Jann Blackstone is the author of "Ex-etiquette for Parents: Good Behavior After Divorce or Separation," and the founder of bonusfamilies.com.