I like to talk about the inspiration of life. Real life. Not the "happily ever after" Disney junk. And it seems life doesn't get any more real than marriage. Last summer's paint job made that pretty clear...still recovering from that ;)
Sol Stein's book, Stein on Writing. There's an exercise about writing a "Lover's Quarrel in Ten Brief Exchanges." The object is to make it clear the couple are in love and fighting. There needs to be tension, it needs to be explaining the character, it needs to be accomplishing something for the plot, etc. So can I claim that our battles are really research?!
I recently read this Marriage Is For Losers article, by Dr. Kelley Flanagan. In summary, it says there are three types of marriages; ones that are competitions, ones where there's constantly the same winner and loser, bully and bullied, and then ones where each person tries to let the other win, tries to be the biggest loser for the good of the couple. To quote the article, "But a decision has been made, and two people have decided to love each other to the limit, and to sacrifice the most important thing of all—themselves. In these marriages, losing becomes a way of life, a competition to see who can listen to, care for, serve, forgive, and accept the other the most."
Using these three marriage types as an outline, why are my characters fighting? What kind of couple are they? Where do their problems come from? All kinds of writing application.
In the last paragraphs of the article, Dr. Flanagan says that maybe marriages full of mutual surrender is the kind of thing is dog-eat-dog world needs. We need to exchange competition for people. It makes me think of Hunger Games, where winning carries such an awful price.
Personally, I want a loser marriage. I'll have less raw material for writing...but I'm okay with that. I'll watch TV for couple-problem research.