In the newly-released movie “American Reunion,” the latest installment of the “American Pie” series, one of the major plotlines revolves around Alyson Hannigan’s character, Michelle, who has transformed over the past decade from a sexually adventurous coed -- remember that “one time at band camp”? -- into an overworked mom who’s too exhausted to sleep with her husband, former pie-humper Jim, played by Jason Biggs.

The film is just the latest illustration of the by-now-clichéd scenario: man and woman get married, man and woman start losing interest in getting busy every night and, soon enough, man and woman’s formerly hot sex life is as lively as a deflated balloon.

While there is some truth to the cliché -- and the seemingly endless wisecracks born out of it -- it doesn't tell the whole story. What's more, it trivializes the very real stresses that couples may experience as their sex lives ebb. So what's really going on? Well, like everything, it's complicated.

To look at the statistics about marriage and sex, you wouldn’t even know that there was an issue to begin with. “Studies have found that married people have more sex than single people, and they also have more varied sex,” says sexual health expert and best-selling author Dr. Laura Berman, who hosts “In The Bedroom with Dr. Laura Berman” on OWN. ”Oral sex is also more common among married people.”

One of the most comprehensive studies on the subject, which was released in 2010 by the Center for Sexual Health Promotion at Indiana University, confirmed this, compiling statistics on sexual attitudes and habits of 5,865 people between ages 14 and 94. An average of 61 percent of singles reported that they hadn’t had sex within the past year, compared with 18 percent of married people. Looking specifically at those between the ages of 25 and 59, 25 percent of married people reported that they were still having sex two to three times per week versus less than five percent of singles.



Yet, while Indiana University’s data is often cited as evidence that married sex can be hot – way hotter than single, anonymous, no-strings-attached sex, thankyouverymuch -- it doesn’t really reflect the shift that individual married couples notice in their sex lives as the years pass, nor the anxiety that this change can trigger.



Unfortunately, there isn’t conclusive statistical data comparing the frequency of couples’ sex while they’re dating to the frequency of their sex as a married couple. However, it doesn’t take a scientist to understand that, as time passes, their sex lives will take a hit.

It’s human nature to crave novelty, as great thinkers as far back as Pliny the Elder have noted -- it’s what makes new couples want to rip the buttons off each others’ shirts and engage in lingerie-sparked romps until the wee hours of the morning. But eventually, having access to the same naked body night after night is bound to erode its novelty. “Tonight’s the night” becomes “not tonight” -- after all, there’s always tomorrow (and the next night... and the next night... and… okay, you get it).



If your relationship started off hotter, heavier and sweatier than a Florida summer, this sexual shift can be disheartening -- even a little scary -- as you start comparing your married sex life to the one you had early on in your relationship (or to the assumed steamy sex lives of your fellow wedded friends).



This is where the complications about married sex begin: When you start worrying about not having sex -- and what that might mean about you, your spouse and your spouse’s attraction toward you.



Sure, plenty of relationship advice books declare that anyone can reignite the spark in their marriage, with a whole spectrum of tips from recreating the courtship mood through role-play to scheduling mandatory date nights. However, it’s impossible to replicate the passionate, falling-crazy-in-love phase of a relationship. What most of these books won’t tell you is that that’s okay. So what if some nights you’d prefer binging on Chinese food and watching “The Biggest Loser” to ripping off each other’s clothes? Isn’t that what marriage is about -- being forever bound to someone who will love you even when the chow mein you just inhaled saddled you with a massive food baby?

While a couple’s sluggish sex life can create dramatic tension for a movie plotline, in real life the pressure that couples put on themselves to reenact the early days of their love affair can cause more issues than their lack of sex.

“A big problem in marriage is that one or both people start thinking something is wrong with them because they're not having sex as much as they think they should. When you start comparing your sex life to what you think it ‘should be’ and conclude that you fall short -- well, that’s a problem,” says psychologist Harriet Lerner, Ph.D., author of "Marriage Rules." "Often, lack of sex doesn't mean anything else is wrong in your relationship. Sexuality is vulnerable and often has a life of its own apart from how your marriage is doing.” (Lerner’s perspective is particularly timely as Lifetime debuts its new show, “7 Days of Sex,” later this month, in which real-life couples are challenged to have sex for one week straight with the hope of “saving their marriage.”)

This is not to say that couples should resign themselves to sexless unions. The foolproof solution for couples wanting to have more sex is simple: have more sex. Experts agree that the more you do it, the more you want to do it, which is far more encouraging than the oft-quoted axiom, “if you don’t use it, you lose it.”



Lerner even suggests that couples go about getting it on even when they’re not in the mood. “If you wait to have sex until one or both of you genuinely feel desire, you'll wait too long,” she says. “In marriage there is often at least one person in the couple who won't feel a natural desire to initiate sex. Push yourself to get started even if you're just doing it for your partner's pleasure.”



As sterile as this advice might sound, the just-as-unsexy truth is, “For all the safety and security that marriage can bring it’s not easy to have ‘good sex’ with the person you live with year in and year out,” Lerner says.

Adds Berman: “You can’t expect wild sex to happen on a regular Tuesday night unless you put it in a little effort. If you want more romance, then be more romantic. If you want more sex, then initiate sex more often.” Basically, put down the take-out, turn off the TV and bring sexy back already.



Yet, while the experts’ solution to having more sex is straightforward, how individual married couples relate to their lives can remain emotionally complex. In marriage, spouses exclusively give sexual pleasure to each other, therefore whether or not they have it can be closely connected to how they think they measure up as partners. It doesn’t help that sexual desire can be a tricky fire to ignite, as it often requires harmony from heart, head and, well, loins.

At the very least, couples can try to stop engaging in the most libido-crushing activity of all, which would be to dwell on -- and beat themselves up over -- all the sex that they’re not having. Leave that to the single people.