Relationship with in-laws impacts how long marriage lasts

What her daughter-in-law may hear is "you're a terrible mother," Orbuch said. It won't be shrugged off as "that's just her and she's worried about nutrition." It will be internalized and analyzed. And then, said Orbuch, "we bring the stress into our relationships with our husbands."

Handling it

As for the solution, Orbuch recommends that women set emotional boundaries with their in-laws and recognize that the relationship is not the same one you'd have with your own parents. Also, don't take everything personally. She also advises learning to say "No."

If, after setting boundaries, tensions remain, talk to your husband, she tells wives. But don't say "you need to fix this." Focus rather on things like "I am feeling uncomfortable and can you help me fix this?" Recognize, as well, that it's his family and it may not be easy for him.

Karen Sherman, a psychologist, author and educator in Long Island, N.Y., pointed out that accepting differences and not making everything personal can go a long way to help families mesh for the long haul. The key is treating each other with respect. You also have to treat yourself that way, though.

"If others overstep boundaries, it's OK to reassert yours, but again, respectfully," Sherman said. (She had nothing to do with this research.)

"We all need to get along with our in-laws and make an effort," Orbuch said. "Nothing in this study says getting along or trying is negative. It's how close you feel and the dynamic and if you can set boundaries."

There are big gender differences when it comes to relationships. Men and women think about and analyze relationships differently.

"Men do relationships and then leave it. They go and do something, then come home and move on to the next thing," Orbuch said. "Women are constantly thinking and talking about and analyzing relationships. 'I wonder why she said that.' Or, 'Did I say the right thing? Maybe I shouldn't have said that.'"

Men do relationships side to side, participating in activities, watching movies, on sports teams, hanging out. Women do them face-to-face. That's one reason, in fact, that men may describe a platonic relationship with a woman as being the closest he's had, because it's a different kind of friendship than he's used to.

For the parents

There's a message for the parents to be found in this study, said Orbuch.

"If you're the parent of a son, tread lightly with your daughter-in-law. She may be more sensitive to your comments. As a golden rule, don't give advice unless you're asked, then offer tips and strategies.

"If you're the parent of daughters, it's really important to be open to bonding with your son-in-law. Remember how important it is for you to get along and learn to be flexible and accepting. If you're going golfing with your sons, invite your son-in-law. It's good for your daughter."

David Cunningham, a communication expert with Landmark Education, who was not involved with the study, said that expressing affection for people goes a long way to helping relationships. It's natural, he noted, to worry about what others think. If you let them know you think good things, much of the pressure comes off a relationship.

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