I asked a marriage counselor for the 3 most common sex and relationship problems she sees, and they turn conventional wisdom on its head

Courtesy of Rachel Sussman

Whatever marriage problem you have, she's probably seen it before. Rachel Sussman pictured.

• Marriage and relationships can be challenging.
• New York City-based marriage counselor Rachel Sussman shared three compelling insights related to sex and relationships, including the idea that "opposites attract" isn't always true.
• This post is part of Relationships 101, a series which aims to help us all be happier and healthier in love - and to stop fighting over who should take out the trash.

Rachel Sussman has seen it all.

At this point in her career as a marriage counselor in New York City, there's seemingly no sex or relationship topic (and I've broached many) that can shock or embarrass her.

Over the course of the past year, Sussman has shared with me a ton of insights related to modern coupledom. Here are the three that I found most compelling:

Couples with mismatched libidos aren't doomed to an unsatisfying sex life

According to Sussman, the most common sexual problem among the couples she sees is mismatched sex drives.

Typically, she said, one person wants to have sex more often than the other, who's either happy with the amount of sex they're having or wants even less. (Though Sussman said the men she sees in her practice typically have higher sex drives, she's also seen many heterosexual couples in which the man has the lower sex drive.)

Sussman's approach is two-pronged. She'll work with the person whose sex drive is lower to see if there's anything they can do to increase it. She'll also work with the person whose sex drive is higher to be patient with their partner and to manage their expectations around sex.

She might even give the couple "exercises": For example, they have to try snuggling and the partner with the higher sex drive has to resist the urge to initiate sex.

You have to work to maintain passion in your relationship

Many couples come to Sussman worried that something's wrong with them, she said, because they're not as passionate as they used to be.

But this, she tells them, is totally normal.

When it comes to passion, Sussman said, "People think, 'Oh, it should just be there,'" Sussman said. "No! It shouldn't just be there. You have to create it."

Sometimes that means scheduling sex dates. Sometimes it means trying something new together. Above all, it means relaxing and realizing that the only real problem is your expectation of magic.

'Opposites attract' isn't always true in the long term

"The way I see it is, opposites attract and with the passage of time, a lot of couples tend to resent the things that are opposite," Sussman said.

For example, one partner in a couple might be highly social and outgoing and the other might be more of a homebody. Initially those tendencies might complement each other, Sussman said; the couple might even say, "we balance each other out."

The problem is that over time, "people get more set in their ways" and there's less opportunity for compromise or mutual understanding.

Your goal shouldn't be to date a carbon copy of you, but to recognize when your partner's habits deviate from yours, as opposed to brushing those differences under the rug.