Stress "forces all of us to say, 'Who's on my team? Are you my ally or are you an enemy?" says Thomas Bradbury, a clinical psychologist at the University of California-Los Angeles who has studied newlyweds since 1990. "Stress is a test, and you will learn very clearly from this test whether your relationship is strong or not."

Even though about two-thirds of couples who marry live together first, Bradbury and other researchers say marriage changes a couple because society looks at them differently than cohabiters. And, because fewer people overall are getting hitched, there appears to be greater interest in newly married, as experts hope to unlock the secrets of long-lasting relationships by starting at the very beginning.

"Newlyweds are pretty happy in the beginning; many of them become unhappy over time," says Jim McNulty, associate professor of psychology at the University of Tennessee in Knoxville. He has studied newlyweds for 15 years and directs the university's Newlywed Project Research Laboratory.

That first year of marriage so intrigues researchers because they know how precarious those early years are. Most divorces happen in the first five years, Bradbury says, which is also when couples often finish education, move or have a child. "There are a lot of really interesting transitions that happen in that period, and a lot of relationship dissolution also."

Some researchers, such as McNulty, have focused on a subject such as forgiveness, while others examine conflict or commitment. As stress has increased in our daily lives, there's particularly strong interest now in its relationship to resilience and how partner interactions over the first year chart the course for the relationship.

CarloGabriel Reyes, 33, and his wife, Yanira Reyes, 29, of San Antonio, are attorneys who met as first-year law students in 2006. Although their jobs are stressful, they don't like to bring job stress home. But the couple are feeling some stress now as they house-hunt. They offered a contract on one house but didn't get it.

"It has been stressful - more for me than for him," she says. "I've been in this apartment longer, and I feel like we need to start our lives. I'm a bit more eager to find something."

Whatever the stressor, CarloGabriel Reyes says the couple, who lived together a year before they married July 9, work it out together. "We're going to get through it," he says. "When one is stressed, the other is there to provide some perspective and calm the other person down."

The impact of stress on newlyweds is "getting a lot more empirical attention," says social and personality psychologist Gian Gonzaga, senior director of research and development at the dating website eHarmony. Its study of 602 newlyweds in Southern California is noteworthy for the number of participants and the level of detail, including extensive pre- and post-wedding questionnaires, videotaped partner interactions, face-to-face interviews and periodic reports through their fourth anniversary.

This work at the Santa Monica-based company's lab began in 2008 and will end in 2014. The 301 couples include 51 matched by eHarmony, with the rest recruited elsewhere in the area.

Findings released to USA TODAY show that even though we may think stress hurts relationships, that's not always true. Also, the study found that a partner's support is a crucial element in coping with chronic stress and in marital satisfaction; if a partner is bad at being supportive, it makes things even worse, Gonzaga says.

"This points to the fact that your partner really has a big impact on how you're going to respond," he says.

"Are you compatible in the way you give support? If you're someone, when stressed out, who needs a partner to listen to you vent and manage your emotions, you need a partner to do that well, as opposed to a partner who is good at giving advice and finding solutions but is really bad at giving emotional support. You want to make sure those ways of having support from a partner are going to mesh with each other."

Stress can help relationship

The eHarmony study found that acute stressors - individual life events that can be stressful, such as becoming unemployed, undergoing a work reorganization or changing schools - can actually benefit relationships if handled right, he says.

Similar research on stress resilience in early marriage, co-authored by Lisa Neff, an assistant professor of human development and family sciences at the University of Texas-Austin, shows that "under certain conditions, stress can enhance the durability of a marriage." That research was published in November in the Journal of Personality and Social Psychology.

In the eHarmony study, 39 percent reported at least one area of high chronic stress (lasts over a period of time) during the first year of marriage. The specific areas include chronic stress from in-laws, work and finances, each of which were identified by 12 percent of participants. Researchers found that relationship satisfaction declined 61% percent faster for those under high chronic stress who had unsupportive partners than for those with low stress and high support. For those with high chronic stress, a supportive partner made the stressful effect disappear.

"If they perceive their partner is there for them and supportive of them, it buffers and reduces that impact of chronic stress," Gonzaga says.

Researchers also found that couples who started their marriage with high chronic stress tended to report declines in relationship satisfaction 36 percent faster than those with low chronic stress.

"It's one of those things you really want to pay attention to," Gonzaga says. "Was he there to listen to your emotions or give you advice? Are they there in the way you need them to be for you?"

New research by Neff, yet unpublished, measured the stress hormone cortisol in 147 newlywed couples and found that on days that wives received social support from their partner, the wives were less physiologically stressed, suggesting they benefited from the support. To gauge support, partners were asked whether "your spouse listened to or comforted you," "tried to make you feel loved," "showed an interest in the events of your day," or "helped you with something important."

For men, findings were a little different; on days that husbands received support from their wives, they showed greater physiological stress. "Men are often socialized to be independent problem solvers, and thus receiving support can be more distressing for men," Neff says.

But that doesn't mean women shouldn't offer support to their husbands, she says. Her research specifically asked about "visible" support, and she says some research has found that behind-the-scenes support may be more beneficial to some, including men who might view visible support as threatening to their self-esteem.

During times of stress, Evan Woolley, 30, of Brooklyn, N.Y., and his wife, Alexis Rubin, 31, "wind up talking about it," says Woolley, who works in real estate finance.

"He's supportive," says Rubin, a middle school teacher. "We always work through things together."

They knew each other almost seven years before their July 16 wedding, including living together for a year in Los Angeles and four years in New York before their marriage.

Kira Birditt, an assistant research professor at the Institute for Social Research at the University of Michigan in Ann Arbor, is studying 373 newlywed couples in the Detroit area, 174 white and 199 black. Her latest work, accepted by the journal Research in Human Development, found that although the conventional wisdom is that all marriages decline in happiness over time, that's not true - she found that declines in happiness occur only in some couples. The research also found that more than a quarter of those who reported the highest happiness levels nevertheless divorced.

"A low level of marital happiness is not the only predictor of divorce; happy marriages may also end in divorce due to stressful life events, low commitment and negative communication," the study says.

It's not like living together

"There's a bit of a shock that happens afterward, when the party is over and all of a sudden a marriage begins and there are all of these unanswered questions," says Kim Perel of New York City, who co-edited Wedding Cake for Breakfast: Essays on the Unforgettable First Year of Marriage, out in May, featuring reflections by 23 women. "Many couples are living together now before they get married, and they think nothing will change, but really, marriage does change things."

Caitlin Grady, 27, also of New York City, married her husband, Ted, on Sept. 24 and says she has been surprised at how different being married has felt.

"Now that we're married, it has mellowed me out. I feel so calm now in our relationship and our life that I haven't felt before," she says. "I didn't expect it to be different, but it is."

5 tips for couples

Don't let stress sabotage your relationship, says Thomas Bradbury, co-founder of the UCLA Relationship Institute. His advice:

  1. Get stress on your radar. Learn to recognize when your partner is feeling stressed, and cut him or her some slack.
  2. Step up. When your partner is tired and stressed, that's your signal to step up and do more around the house, Bradbury says. "But if you crow about helping, you are making your partner feel worse, not better."
  3. Build a firewall. Partners in healthy relationships "know how to prevent ordinary frustrations from spilling over to erode the good feelings that they have for one another," Bradbury says. "So build a firewall around all of the great things you and your partner share, and protect them against minor annoyances."
  4. Strengthen the foundation. Good relationships are fundamentally about two people taking care of each other. Figure out what your partner needs to feel secure and happy and do your best to give it to them, and on their terms, not yours.
  5. Get active. If stress is eating away at your relationship, get on your feet and invite your partner to a walk, a class or a movie.