Happy relationships shouldn't be hard work.

That's one of the upbeat findings from my landmark study of marriage, which has followed 373 married couples since 1986. Here's more good news: If you're in a happy partnership, married or not, you can keep it that way, or make it even better, by introducing a few new behaviors and small changes.

While many relationship experts say you need to focus on fixing what's wrong, my research shows that adding positive behaviors to the relationship has a much greater impact on couples' happiness.

Here are four things you can start doing now to make your relationship happier, more passionate, and more fun:

1. Get real about your expectations. Do you wish he had rippling abs and a million-dollar bonus? Or that she was a football fanatic and perked up with an 18-year-old's libido when you roll into bed at 2 a.m.? Sure you do, but how likely is that? Having unrealistic expectations leads to frustration, and my study found that frustration is the main reason relationships fail.

Try this: Write down your top two relationship expectations on a piece of paper, and ask your partner to do the same. Now, switch papers and discuss. Are your expectations reasonable? How can you make them more so? This simple exercise helps you see what's really important to your partner, and puts everything else into perspective.

2. Do small things, often, to make your partner happy. In my study, couples who gave affective affirmation to each other regularly were the happiest. Affective affirmation consists of compliments, help and support, encouragement, and subtle (nonsexual) rewards, such as hand holding. Key finding: Men crave affective affirmation more than women, because women typically get it from people other than their husbands. When men don't get it, they become distressed.

Try this: Tell your guy he looks great in his outfit. Or spontaneously give your gal a hand with the dishes. Send your man a middle-of-the-day sexy email. Or fill up your gal's tank with gas. You'll be delighted to see the effect of such small gestures that show you care.

3. Practice the 10-Minute Rule. Most couples think they talk to each other all the time. But how often do you talk about things that really deepen your understanding of your mate? The happy couples in my study talked to each other frequently—not about their relationship, but about other things—and felt they knew a lot about their partners in four key areas: friends, stressors, life dreams, and values.

Try this: Set aside 10 minutes a day to talk to your partner about anything other than work, family, the household, or the relationship. Ask her what her favorite movie is, and why. Ask him to recall a happy memory from childhood. Ask her what she'd like to be remembered for. Ask him to name the three worst songs of all time. Do it at dinner, before bed, anytime—as long as you do it for 10 minutes every day. This simple change infuses relationships with new life.

4. Knock each other off balance. Want to get more passion into your romance? My research shows that the best way to do this is by implementing change. The changes can be small, but they have to upset the routine enough to make your partner sit up and take notice.

Try this: Switch roles. If he always makes the dinner reservation, let her do it. Or interrupt routines: Play hooky from work and do something fun together, like taking a day trip—or try something new like a water-skiing class, or an African drum workshop.

Remember: It doesn't take much to shake things up and infuse your love life with surprise, fun, and excitement. Introducing small changes and attitude shifts is the key to maintaining a happy love relationship.

About the Author

Terri Orbuch, Ph.D.

Terri Orbuch, Ph.D., is an Oakland University professor and research professor at The University of Michigan.

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