And yet, most of us use sexual compatibility as a guiding force in gauging how “right” a relationship (or potential relationship) is – regarding sexual incompatibility as the ultimate deal breaker.

Below, three experts explain what this make-it or break-it factor really means, and share best practices for determining whether it exists, can be worked on, or is a lost cause.

“This simply isn’t something that would be listed in the DSM or dictionary,” Dr. Christopher Ryan Jones, PsyD, a clinical psychologist with a specialty in sex therapy, says.

But Psychology Today offers this definition: “It’s the extent to which a couple perceives they share sexual beliefs, preferences, desires, and needs with their partner. Another form of sexual compatibility is the extent to which similarities exist between actual turn ons and turn offs for each partner emotionally, cognitively, and behaviorally.”

Good question. Basically, sexual compatibility comes down to how well your individual beliefs, needs, and desires around sexual activities mesh.

• definition of sex
• frequency and duration of desired sex
• preferred “environment” for sex
• turn ons and turn offs
• relationship orientation

Specific sex acts: Do you more or less enjoy the same moves, or does everything you do in bed require that one of you compromises?

“The more similarities you have in your answers to those things, the more sexually compatible you are,” Dr. Jones says. Makes sense.

Being up-front about your sexual preferences (that likely requires some self-reflection!) is only way to know how sexually compatible you truly are.

Ask 100 sexually active folks what “sex” means to them, and you’ll get 100 different answers. That’s because everyone has a different understanding of what “counts” as sex.

Some people see P-in-V as the defining feature of sex, while others see anal, oral, and manual sex as, well, sex.

There’s no wrong definition of sex. But “having similar definitions of sex, or at least sharing your definitions, is an important element for operating within similar expectations sexually,” Jenni Skyler, PhD, LMFT, and AASECT certified sex therapist, sexologist, and licensed Eve, says.

According to Dr. Jones, two people with different beliefs around whether sex before marriage is OK can be in a happy healthy relationship. “More important than sharing that same view is having a proper understanding of each other’s views on sex, and respecting that.”

But there are some places there shouldn’t be compromise. “Couples have to be on the same page when it comes to the structure of their relationship and level of commitment,” Skyler says. “If not and one person wants monogamy and the other wants an open relationship, the relationship is doomed.”

For instance, if you’re poly and reserve fluid bonding for your primary partner, but have unprotected sex with someone else, that would constitute as cheating.

Sexual compatibility is about more than just if you have sex before or after marriage and with just each other.

There’s probably some wiggle room here, but if you want to bone with the lights off to Lana del Rey and your partner wants to bone to The Grateful Dead in the day time, there might be some rub.

How long you go for: Face it, 5 minutes of getting freaky looks and feels way different from 5 hours. If you enjoy marathon sex and they do too, go ahead and get after it like bunnies (or jackrabbits)!

Environment: Things like where you like to have sex, whether the lights are on or off, if and what music is playing, and room temperature all factor into your preferred sexual atmosphere

How often you do it: Just on anniversaries? A few times a month? Once a week? Multiple times a day? There’s no “right” or “normal” sex frequency, but you want to be in the same ballpark.