Happy, affectionate couples: In a world where 40 percent of marriages end in divorce, you can’t help but notice them. And maybe gawk a little. There they are, always finishing each other’s sentences or laughing in some dusky corner of your favorite wine bar. They seem so wonderfully in sync, and they make the work of being a couple seem so d*mn easy. Of course, no relationship ever is, especially once you add in life’s little pressures, like your crazy boss, laundry and your spinning habit.

But there are certain core values that make some relationships more intimate and resilient than others. You could easily predict the list: trust, respect, commitment and a strong team spirit in the relationship. Experts say it IS surprising that when you ask loving husbands and wives about the key to their successful relationship, over and over you’ll hear the same things, habits that mirror these values. Learn these secrets and enjoy a happier, closer relationship with your man.

1. Use pet names

Sure, you may find it obnoxious when you overhear other couples talking like toddlers, but endearments are actually a sign of a healthy connection.

“Pet names take you back either to the happy childhood you had or the one you wish you had,” says Manhattan-based family therapist Carolyn Perla, Ph.D. “They signal a safe, supportive environment.” Also, these days, when we’re stretched to the limit trying to juggle the stresses of our lives, “pet names give us the chance to let down our guard, to be vulnerable and childlike. And they make us feel close to one another.”

If you find pet names just too annoying, these same feelings of intimacy can also come from using a special tone of voice with each other, sharing “inside jokes,” or pet-naming your spouse’s intimate body parts. The point is to connect with some private message system that’s meaningful to the two of you alone — not to the outside world. “This type of playfulness is a statement that you’re feeling comfortable with each other and with the relationship,” says Dr. Perla.

2. Do stuff together

When that pheromone-crazy feeling of falling in love passes and happy couples no longer spend all day in bed, they look outward. They start businesses, join a softball team or take up cooking together.

Of all the variables in a relationship — from commitment to communication — the amount of fun couples have together is the strongest factor in determining their overall happiness. So even if your life is impossibly frantic, make the time for play. And do all you can to eliminate distractions. Close the computer, turn off the tv, and ditch the cell phone. The activity doesn’t have to be anything elaborate or costly. Exercising together, browsing the mall, or renting a classic movie can help bring the two of you closer.

3. When the going gets tough, don’t call Mom or Dad

The first task facing all young couples is separating from their families of origin, points out San Francisco-area-based family researcher Judith Wallerstein, Ph.D. This doesn’t mean you shouldn’t go home for the holidays. But if there’s a crisis or good news about a big raise or the results of a medical test, you as a couple should talk about it together first before dialing Mom.

4. Stay connected to their parents

I know what you’re thinking. Doesn’t think contradict number three? Nah. You can talk with your mom every day if you want and still be clear about where your relationship to her ends and your love for your partner begins.

Staying connected to parents, siblings, cousins and the like can be excellent for a relationship because it gives a sense of family continuity. It generates positive feelings, especially when you incorporate your significant other into that family. You’re sharing that part of you with each other.

5. Don’t nickel-and-dime about chores

It’s no secret to most of us that most women continue to do more in the housekeeping and child-rearing departments than their boyfriends or husbands. Still, when partners become double-entry bookkeepers, adding up every dish washed and every bag of trash taken out, they may be headed for trouble.

“Most couples think they should strive for a relationship that’s 50-50,” observes Dr. Perla, “but the fact is, they should each give 150 percent. In good relationships, couples give everything they can. They don’t nickel-and-dime each other, and they respect that each person gives different things.”

6. Fight constructively

There’s fighting and then there’s fighting. When couples start yelling and throwing things, when they bring up every single complaint they’ve ever had, you can be sure that they won’t be celebrating their silver anniversary together. “Studies show that the way couples handle conflict is the most important factor in determining whether or not they stay together,” observes Polly Young-Eisendrath, Ph.D., a clinical associate professor of psychiatry at the University of Vermont.

Happy couples learn the art of constructive arguing. In strong relationships, the partners take control of their disagreements by establishing ground rules. They may, for example, call an agreed-upon time-out if the conflict is escalating and unproductive. They also truly listen to each other and won’t try to solve the problem before they’ve heard each other out. Above all, no matter how angry they get, they don’t resort to name-calling and insults — key danger signs.

7. Give each other gifts

Couples who are deeply in love often give each other presents or write little notes, says Thomas Moore, Ph.D., best-selling author of Care of the Soul. What they’re doing is preserving the rituals, and the magic, of their courtship. Who doesn’t love a little romance?

One caveat: the gift should carry no strings. If you come home from work to find that your man has prepared a candlelight dinner, it shouldn’t be an expected prelude to sex.

8. Never lose their sense of humor

Humor, as many of us already know, is the super glue that keeps a couple together. When a couple can no longer laugh together, it’s a signal that the heart has gone out of their relationship and they are headed for trouble.

But lighthearted couples never mock each other. They instinctively know what is — and isn’t — fair game

9. Take “for better or for worse” seriously

Contented couples encounter their share of life’s miseries — whether it’s the car breaking down, a nasty cold or a missed promotion — but they help each other get through. You don’t, for example, hear them say, “How could you let that happen?” when a spouse loses a job. “Couples who do well together tend not to do anything that increases their partner’s suffering, like become resentful or criticize,” notes Dr. Young-Eisendrath. In good marriages, people feel safe from the outside world.

Healthy relationships will make it because both partners keep trying. They know these secrets and work hard to keep these habits – even if it look effortless to the rest of us. Do you have any of your own happy couple secrets?