A woman tells her husband she's starting a diet, and the next day he brings home two gallons of ice cream and a box of Oreo cookies.
A man calls his daughter and they talk for an hour about how bad his son (her brother) is behaving, things going on at the son's job, and what they think about how the son is raising his kids.
A woman dreads visits from her mother because her mother will look all over the house to find fault with her housekeeping, then spend the rest of the visit giving helpful "advice" about how she's spoiling her new baby. The woman has argued with her mother about that negativity, but the mother then sobs that she's only trying to help and will sulk for a week.
If you're a writer, you're going to encounter all these situations. More to the point, you're going to have to create them from whole cloth.
Therefore, and this may sound obvious, if we don't understand the basics of relationship dynamics, we cannot write realistic fiction. In fiction, character is where the rubber meets the road. And character expresses itself in relationships.
The first instance is something called a push-back reaction. Everyone does it. Why? Because we're comfortable with our loved ones just as they are. And therefore when a loved one makes a change, even a good change such as going back to college or beginning a diet and exercise program, we unconsciously make it harder for them to continue that path because we don't want the relationship to change.
The second instance is called triangulating, where two people have a relationship at the expense of a third. It keeps everyone's feelings carefully tamed but prevents any actual growth, and of course it prevents a genuine relationship between the two conspirators and the person on the third point of the triangle.
The third instance doesn't necessarily have a name, but those two clearly need to have a discussion. The problem is, whenever they fight, they fight in a way that reinforces the negative dynamic rather than addressing the actual problem (that the woman is ready for adult autonomy and her mother doesn't want to let go.)
A writer needs to become fluent in relationships. This isn't optional. The same way a writer needs to learn to manage dialogue, setting, punctuation and complex sentence structure, a writer also needs to become fluent in boundaries, push-back reactions, triangulating, and how to have an effective argument (although a lot of your story will probably have arguments of the ineffective, status-quo-reinforcing kind.)
Read self-help books. Read books about motherless daughters (Hope Edelman), about raising adopted children, about setting boundaries in relationships (Townsend and Cloud). Browse your used book store and pick up What Color Is Your Parachute even if you're not going to look for a job for ten years. Read books about basic psychology (our own Carolyn Kaufman has one of those!) and dealing with sociopaths (Martha Stout). Read, read, read.
If you're unsure, then start with The Dance of Anger and The Dance of Intimacy by Harriet Lerner, which is where the above examples come from. Even if you don't write these specific dynamics, knowing how the human heart operates can only improve your fiction.
Jane Lebak is the author of The Guardian (Thomas Nelson, 1994), Seven Archangels: Annihilation (Double-Edged Publishing, 2008) and The Boys Upstairs (MuseItUp, 2010). At Seven Angels, Four Kids, One Family, she blogs about what happens when a distracted daydreamer and a gamer geek attempt to raise four children. She is represented by the inimitable Roseanne Wells of the Marianne Strong Literary Agency.