A few years ago, on the road trip leading up to our marriage, I made a significant sacrifice. It happened on the New Jersey Turnpike. That was the moment when I deleted all the pictures of penises from my phone.

It wasn’t much of a collection. My pal Mandy has an impressive menagerie of penis pictures sent to her over the years. Men love photographing their junk. The reason we’ve seen such rapid improvements in the cameras on mobile devices is because guys over at iPhone keep asking, “How can I take better photographs of my junk?”

Although I didn’t have many junk photos, each never failed to bring a smile to my face, amongst other physical reactions. Removing them was a symbolic gesture, making clear I had selected the manly parts I would like to gaze upon for the rest of my life. I could go in the kitchen right now and request to view Preppy’s junk, and though he might be confused by the sudden demand, I could score a quick peek if I asked nicely.

That’s one of the concepts of monogamous marriage that was extraordinarily appealing. After all those years of sleeping single in a double bed, I’d have my very own dedicated lifelong bedroom playmate. Yes, marriage is a sacred, beautiful thing, but a perk that often goes unheralded is the simple filthy value of there being one person in this world who knows exactly what gets you off. That freakin’ rocks.

Thirty years down the road, Preppy will be able to close his eyes and remember what I looked like in my twenties. He won’t see me as just some naked middle-aged man, the way a stranger would. The shared history will make us beautiful.

However. The downside of this is that if your dedicated bedroom lifelong playmate ain’t in the mood, you are officially out of luck. No nookie for you, which will test the limits of your patience/sanity. You will mentally review the agreement: You vowed to have sex with this person exclusively, and then after they secured that promise, they stopped having sex with you. In those tuck-it-in-the-waistband-and-move-on moments, monogamy can feel like a dirty little trick specifically designed to cause sexual frustration.

Here’s the truth: Once you settle in to a life together, there is always one person in the relationship who wants the sex, and one person who determines whether the sex is gonna happen. For our purposes, we will call these individuals “Yes Please” and “The Decider.” I can hear some of you scoffing at this notion.

“Oh, silly Topher,” you scoff. “Our sex life is a beautifully organic blossoming expression of our love, emerging through circumstance and scenario.”

You only think that because you are The Decider. You just described how sex happens for you. If I asked your partner how and when sex happens, their answer would eventually boil down to it happening whenever you say so.

To be clear: Either party has the authority to determine when the sex absolutely isn’t going to happen, but only The Decider holds the power of announcing when it is. The Yes Please/Decider relationship is unrelated to gender, age, or orientation. My sister is a Decider. Mandy is a Yes Please. I am a Yes Please.

Sometimes a Yes Please will attempt revolt, trying to gain the upper hand by withholding sex from The Decider. This is a fool’s errand, as the Yes Please will inevitably cave when presented with the option of perfectly good sex, right there for the taking. Often this revolt will go entirely unnoticed by The Decider.

I remain convinced that the source of many sexual conflicts in relationships is that one party or the other has not acknowledged who The Decider is. If you don’t believe me, bring it up. Marriage is basically just a series of loving negotiations punctuated by errands.

Once you’re both on the same page, the Yes Please can ease up on the “How about tonight?” entreaties, because you both accept that Yes Please is pretty much always up for it and just waiting for a cue. The Decider, meanwhile, experiences something akin to a superhero origin story: Yes, you have an awesome power, but with it comes great responsibility.

Topher Payne is an Atlanta-based playwright, and the author of the book “Necessary Luxuries: Notes on a Semi-Fabulous Life.” Find out more at topherpayne.com.