Q: My ex and I have been divorced for six years. Our daughter has been playing competitive soccer for the last two years. Her father was her coach and they traveled all over the state. She excelled, I will admit that, but it just to be got too much for our family — and it's very expensive. My current husband and I (we have two children together) made the decision to transfer her into parks and rec soccer. Her father was furious and will not attend any of her games. I think he's being petty. What's good ex-etiquette?

A: Get ready for an eye opener: Both of you are guilty of being petty. You just as much as Dad. The irony is that you see only Dad's bad behavior and your bad behavior is at the center of the problem.

Here's your red flag: You have one family — a new husband and two more children. Your daughter has two families. She's one little person living in two different homes trying to juggle her allegiances to two very different parents. Would you want to live that way? Probably not.

In your defense, juggling past and present can be a daunting task, but it's something you take on when you move on after a breakup, and it makes the need to co-parent successfully even more important. As a co-parent, it's your responsibility to discuss all desired changes with the child's other parent before any changes are made. An arbitrary decision undermines trust. The other parent will take it very personally, especially if he or she is invested in something specific with the child, like coaching her team. As a result, the two homes break into factions — one house against the other — with the child in the middle.

Here's Dad's red flag: He's so angry that you made an arbitrary decision, he's refusing to go to your daughter's games. He thinks he's getting back at you, but anger has clouded his reason. Rather than hurting you, he's hurting his child. Being spiteful, revengeful or vindictive only perpetuates like behavior, puts your child in the middle and demonstrates firsthand that acting in a spiteful manner is acceptable. It is not.

What could you have done? You should always begin by having a conversation with the co-parent. This demonstrates respect. If you had spoken to Dad before a decision was made, you could have brainstormed solutions. There were lots of things Dad might have suggested if given the chance. Since he was so active in the other league, he might have offered to transport the child to games, start a carpool or even pay most of your daughter's soccer fees if he wanted her to continue that badly. You don't know. You never asked.

Remember that you don't have to come up with a solution all by yourself. There's someone else you can consult for help: your child's other parent. I know this does not come naturally. It must be cultivated in the best interest of the child you share — and when you do, that's good ex-etiquette.

Jann Blackstone is founder of bonusfamilies.com.