Write a scene in which a man and a woman go into a mattress store to buy a bed. The couple can only talk about the bed, but must nonetheless reveal through the conversation the real situation between them. (For an example of how this kind of scene can work, read Hemingway's "Hills Like White Elephants.")
To begin, you might consider the many different stressful situations that develop between couples: divorces, pregnancies (as with "Hills"), substance abuse issues, transfers, etc. If you're having problems thinking of a conflict, start with a situation from your own experience. The situation doesn't matter as much as the conversation. The exercise will force you to think about how couples communicate, how much goes unsaid between them. At the same time, when you're done, your reader should have a very good idea of what is happening in the lives of these two people.
In doing this exercise, you may want to review the basics of writing dialogue first. For more insights on writing and teaching, read the entire interview with Alix Ohlin. Or try out other creative writing exercises.
