A long-term, enjoyable marriage is possible.

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Interpersonal Ingredients: Hallmarks of Happy Couples

It doesn't take a trained statistician to guess certain key ingredients to a happy marriage. According to the 2011 report from the National Marriage Project, husbands and wives cited sexual satisfaction, commitment and positive attitudes about child-rearing among their respective must-haves [source: Luscombe]. Add to that solid communication skills and extramarital social support, and the basic toolbox for weathering the years together is filled [source: Parker-Pope].

But pursuing love throughout a marriage also involves a degree of selfishness, come to find out. Stony Brook University psychologist Arthur Aron emphasizes the importance of finding self-expansion in a marriage as means to long-term satisfaction [source: Parker-Pope]. Couples that stoke each other's senses of learning, adventure and intrigue -- either alone or side by side -- are unwitting experts in self-expansion, seeking novel experiences that enrich themselves and, by extension, their relationships. In exchange for that self-expansion, satisfied partners statistically perform five acts of generosity for every one instance of bickering or whatnot [source: Parker-Pope].

If those are the mechanics of a long-term, enjoyable marriage, what does that lasting sweetness feel like? In short, it feels a lot like falling in love. In 2009, psychologists Bianca P. Acevedo and Arthur Aron at Stony Brook University debunked the common gloomy notion that romance eventually fades as a marriage ages. What ebbs over time, rather, is obsession. As couples bond over the years, the passion doesn't necessarily dwindle, just the overwhelming obsession and anxiety that initially came with the budding relationship [source: Acevedo and Aron]. Early-stage romantic love is characterized by a nagging obsession for one's beloved, so strong and blindsiding that it's considered a threat to the human metabolism, gobbling up an astonishing amount of focus and energy [source: Fisher]. In that light, successful marriages are akin to trading out honeymoon suites for penthouses.

At the same time, that isn't to say that making marriages work is a cinch, as evidenced by the fact that Americans' lifetime chance of divorce hovers between 40 and 50 percent [source: National Marriage Project]. For all of these interpersonal tips for nuptial bliss, the difference between the couples who do and don't endure can be seen clearly in the brain.