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Blog Short #142: Why does your friend (partner) have problems when a third person joins in?

Photo by LeoPatrizi, Courtesy of iStock Photo

You have a good friend you love to spend time with, and vice versa. But, if a third person is added to the equation, your friend becomes difficult. She might pout, be standoffish, or say things tinged with hostility. Later when you’re alone, she bad-mouths the other person.

It all sounds rather middle schoolish, doesn’t it? Yet it happens with adults. It might occur with your partner as well.

There’s a psychological basis for this kind of behavior. It has to do with “dyads versus triads.” Let me explain what that means, and then we’ll discuss how you might approach the problem.

A note here: If you’re well-versed in psychology, you know all of this already, but if not, this will be new to you, and it’s good to know.

Okay, let’s start.

The Dyad

Two crucial psychological developmental tasks occur during the first 3 to 3½ years of life. These are separation-individuation and object constancy. I’ll explain them in English for you. But most important to note is that both tasks are accomplished within a dyadic relationship, i.e., mother and child.


As a developing infant in the womb, the baby is symbiotic with Mommy. Symbiosis just means they are one. There’s no sense of separation for the infant.

Once the baby is born, this symbiosis begins to shift. The shift speeds up around seven months when the baby can crawl and explore his environment. Eventually, he can walk and stand without support, which is a major achievement. He recognizes that he and Mommy are not the same. They have different bodies and different wills. This initiates the toddler stage.

The toddler doesn’t know this cognitively because his brain hasn’t developed enough to do that, but he experiences it as he practices moving away from Mommy and then running back to her.

It gets into full swing when his desires begin to clash with hers. He wants to do something, and she says no, sometimes resulting in tantrums.

What’s happening is that the toddler is practicing separating and differentiating himself from Mommy but then becomes anxious about it and regresses. It’s an emotional time, and why it’s referred to as the terrible twos.

The process continues and resolves around 3 to 3½, providing the attachment to Mommy (or the caretaking person) is secure. That means Mom’s present, available, and nurturing even as the toddler has his mood swings.

The culmination is that the child establishes a basic sense of self and becomes comfortable with his new-found individuality.

Object Constancy

The second task, object constancy, occurs simultaneously with the first one.

A simple way to get a flavor for object constancy is to imagine what happens when the young child is away from Mommy. A child who has successfully mastered object constancy can picture her face in his mind and feel connected to her even though she isn’t present. He’s internalized her and all she represents to him so that he can function and feel safe when she’s not around. He knows she’s not gone, just not present at the moment. He doesn’t feel anxious about the separation.

Kids usually master object constancy around the same time they complete separation-individuation. It’s not exact, and some kids develop faster than others. But generally, 3 to 3½ is when the dyadic phase expands to the triadic stage.


During the ages from about 3½ up to 6, children work on becoming part of a triad – Mommy, Daddy, and child. Even if there’s only one parent, children still work on adding in a third person through socialization and relationships with other family members.

If you’ve spent much time around a 4-year-old, you know they’re interested in playing with other kids and like spending time with aunts, uncles, cousins, grandparents, etc. They have a strong sense of self and now want to explore other relationships. They feel confident enough to welcome a third person (and more) into their dyad.

That doesn’t mean, by the way, that Daddy doesn’t have an essential role during infancy and toddlerhood. He, or the other parental figure, is important.

It’s just that the developmental tasks are being accomplished in terms of a dyadic relationship with one parent while the other parent provides a more supportive role.

The Problem

As adults, we assume everyone’s gotten through these phases well enough to operate as autonomous, secure, trusting individuals. Not true.

Although children continue to grow, develop, and eventually become adults, those unfinished developmental issues linger and influence adult emotions and behavior.

If an adult has not successfully developed a strong, healthy sense of self and mastered object constancy, they still operate as part of a dyad.

A person like this can sometimes successfully feel safe and happy with one person, but become uncomfortable when a third person is present or trying to enter into their dyadic relationship.

That doesn’t mean that couples or even best friends don’t have some boundaries with others or that they don’t have a level of intimacy that is theirs. They do, but secure partners (friends) can feel easy around other people and be welcoming without alarming either of the partners.

People who struggle with dyad/triad problems might become jealous or uncomfortable when a third person enters, or maybe shut down if the other partner enjoys interacting with other people. They might also become possessive or punish their partner by ignoring them and giving overly special attention to others to make the partner feel a loss.

Unfortunately, this happens in families when two parents continually triangulate a child, encouraging them to choose sides between their parents.

What to Do

This problem is not easy to fix because it’s rooted in early relationships with parents. Here are some things to try:

1. Acknowledge the problem.

Acknowledge that the problem exists and is real, first for yourself and then with the other person involved.

2. Explore the emotional repercussions.

Discuss how you both feel when this happens without judgment. Someone who struggles with this problem feels pain when it occurs. They might also deny that it exists. But if they can talk about it and admit that it makes them uncomfortable, you have something to work with.

3. Figure out some solutions.

Next, talk about what you can do to make each other feel better when these situations arise.

If you go to a party and one makes the rounds to chat while the other stands aloof or shows discomfort, decide how you can prevent those feelings before you go.

  • You could create a signal to let each other know you need to check in.
  • You could make sure to touch each other here and there to reinforce the connection (for partners).
  • Maybe you make the rounds together and remind each other beforehand that conversing with others doesn’t take something away from the relationship.
  • For two friends, you might decide to make it a project to help the third person feel comfortable and wanted. If you’re doing that together, it solidifies the friendship rather than pulling at it.

Using Cues

The bottom line is that any show of possessiveness, withdrawal, or even hostility comes from a place of insecurity and feelings of loss. If you can keep that in mind for yourself, if you’re the one working with the issue or for your friend or partner, it will help you deal with it.

Offering reassurance is one of the best ways to reduce negative reactions and feelings. This works especially well if you have some cues in place that you both know to use.

Cues maintain the intimacy of the relationship. We use them all the time, but generally in other circumstances. For example, you set up cues with your boss during meetings. You might have cues with your kids to signal that behavior is getting off track. Cues are intimate. So use them.

The Last Thing to Consider

If the problem is severe and you can’t work it out alone, therapy is the best option. Even better is to do both: use the strategies we’ve laid out here and use therapy to deal more directly with developmental issues. You can overcome them, but you must be willing to accept they’re real before you can pursue that.

Resolving these issues will fix many other problems, so the benefits are significant.

That’s all for today.

Have a great week!

All my best,


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