If you ask the average person what breaks relationships apart, he or she might say money, lying or cheating. And that is true. But like death by a thousand paper cuts, there are even more insidious everyday habits that kill relationships too.
For nearly three decades, I've had a front-row seat to thousands of relationships. My ongoing research -- a long-term study funded by the National Institutes of Health since 1986 -- gives me the opportunity to study, closely and over time, critical patterns in marriage and divorce, romance and relationships.  Today, here's what I know for sure: small stuff is a big deal. I cover some of these findings in my upcoming PBS special, "Secrets From The Love Doctor," which will air nationwide starting November 30, 2013.
To create a truly happy, healthy relationship, every couple, of every stripe, should take the most overlooked and under-discussed relationship killers to heart. Here are the six most overlooked relationship killers and solutions to those bad habits.
1. Skipping me-time. Among unhappy couples, more people (11.5 percent) point to a lack of privacy or time for themselves as the reason for unhappiness than they do to their sex lives (6 percent). Many couples say that space, or giving each other plenty of time for self, is the single most important reason they think their relationship survived. Time alone gives partners those vital moments to process thoughts, pursue hobbies and develop new topics to talk about! Too much space or separateness isn't good, but partners who pursue their own hobbies, interests and friends tend to be happier than those who depend on each other for everything.
Solution: Talk to your partner about the benefits of me-time, and emphasize that you still want couple time, too. Don't keep secrets, and share with your partner some of the fun or funny things that happened during me-time.
2. Assuming you know each other. Couples who have been together for many years sometimes believe that they know everything about their partner. Unlike when they were first dating, they stop asking each other questions and learning more about each other. Such loss of curiosity can be lethal. I call this the silent dining syndrome. Couples go out together to a restaurant but then don't talk.
Solution: To stay happy in a relationship, partners need to talk to each other every single day, for at least 10 minutes, about anything other than the home, kids, work or their relationship. Ask questions to each other, just like when you were first dating! A side benefit of getting to know one another again is an increase in passion and excitement.
3. Staying mum about "minor" annoyances. A lot of couples sweep little annoyances and pet peeves under the rug. Over time, though, these small everyday irritations can add up and put a relationship on life support. It's actually the small, everyday irritations that can accumulate if not dealt with and become big problems in relationships.
Solution: Contrary to popular belief, couples need to sweat the small stuff in their relationship to be happy and together over the long haul. Bring up the annoyances in a constructive way--pick the right time and situation to discuss, ditch all other distractions, use your "I" statements, and avoid using the words "never" and "always."
4. Waiting for special occasions to express love. Many couples make the mistake of waiting for special occasions, such as birthdays, anniversaries, or Hallmark-type holidays, to express loving feelings to one another. One key finding from my study is that when husbands do not receive frequent affective affirmation from their wives (defined as words, gestures, or acts that show him he is noticed, appreciated and loved) that couple is two times more likely to divorce.
Solution: Do or say something frequently to show your partner that he or she is valued and noticed. Sometimes a goodbye peck on the cheek or a thoughtful compliment is all it takes to make a partner feel loved and appreciated.
5. Spending too much or too little time with the in-laws. In my study, in-law ties were related to the success of a marriage, but the findings differed depending on whether you're a wife or husband. Married couples were 20 percent less likely to divorce when the man felt close to his in-laws. These ties connect the husband to the wife and say to her: your family is important to me because I care about you. When a woman felt close to her in-laws, however, the couple was 20 percent more likely to divorce. Many women have a difficult time setting boundaries and often take what their in-laws say as interference.
Solution: If you are a woman, put forth effort, but set boundaries and learn to say no. Also, try not to take things personally. If you are a husband, treat your in-laws well and make them feel special.
6. Seeing the glass half full. Many couples only talk about what's going wrong in their relationship. They end up focusing on the negative aspects of their relationship. In my study, couples who also concentrate on what's working well -- on the glass half full -- were much happier over time than those who purely try to "fix" their problems.
Solution: Make a list of the top five things that are going well in your relationship and work on strengthening those positive aspects. Focusing on what's going well in the relationship motivates you both to move forward in that relationship. Also, an optimistic approach will rub off on your partner and attract you to others who are seeing the world as "half full."
 Terri L. Orbuch, The Early Years of Marriage Project. University of Michigan, Institute for Social Research. Supported by a grant from NICHD (HD40778).
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