When I first met Doug on match.com in 2005, we were 26 and living in Washington, D.C., both recently out of serious relationships, both working long hours at jobs we loved. He had a big position with a top financial firm; I headed up public relations for a health-care nonprofit. On our first date, although we only kissed, he told me I wouldn't be the same when he was done with me. I knew he was right — I just didn't know what it meant. Neither of us did.

Doug was tall with dark hair and eyes, but it wasn't his looks that unglued me. A recent business school graduate, he was smart, confident, and witty. We'd talk for hours about politics and sports, and though he commented on how amazing our chemistry was, how amazing I was, he held back emotionally. Control. He had it, always.

We dated for a few months and had intense — if, in retrospect, vanilla — sex. There was a magnetic pull between us, only the attraction swallowed me. I became uncharacteristically needy, and it pushed him away.

Months went by after we'd broken up, but I couldn't get Doug out of my head. I began having fantasies about him like I'd never had about anyone. I wanted him to overpower me. I'd heard about BDSM — bondage and discipline, domination and submission, sadism and masochism — but didn't know much about it. Curious about my new feelings, I did some research online. One site showed women being bound and whipped. Another showed a girl on the floor with a man standing over her asking who she belonged to. The answer: Him, of course. It all turned me on, but I felt confused. Wasn't it weird that I, a proud feminist, could enjoy something so degrading? I would never stay with a man who hurt me. So how could I enjoy this? Still, I kept exploring.

Within a few clicks on another popular site, I found Doug's profile. I was initially shocked, and yet it made perfect sense. That was our connection. I messaged him: "I didn't know you had this side of you. Wink, wink."

At first, we casually texted, catching up on each other's lives. He'd finished an Ironman triathlon, and I'd started working on a business plan to venture out on my own. Our shared interest in BDSM came up slowly, in e-mails and on the phone. He'd joke about making me scream, and I'd say, confidently, "Bring it." Or he'd forward articles or videos of BDSM research he'd done. I learned that BDSM is about more than rough sex. In a D/s (Dominant/submissive) relationship, you have to trust each other — emotionally, mentally, spiritually. While a Dominant, or "Dom," may have the "power," he can only go as far as his submissive, or "sub," will let him. It's not abuse; it's consensual. Doug would text, "How do you feel about a belt? Could you trust me to do anything to you?"

Almost a year after our first date, Doug came to my house to try BDSM. We settled on opposite sofas, and I was a fidgety, nervous mess. What if I didn't like the pain as much as the idea of it? Then Doug stood up, towering over me, and grabbed a fistful of my hair. He ordered me to perform oral sex, but that first time wasn't really about sex, it was about seeing if I'd be obedient. He used a belt, leaving welts on my back, thighs, and bottom. I could hear him pacing behind me, but I never knew when the lick of leather was coming. It hurt like hell, but I was utterly turned on. I had no control. And I loved it.

Afterward, I cried, overwhelmed by how raw it all was. We met up a couple more times for similar sessions, but then I pulled away. I was freaked out. Not by the pain, but by how intense my feelings were for him.

Nearly two years passed before I saw him again. We had both gotten married, gotten on with our lives. My husband and I renovated our house. I traveled to India and Australia with friends. And my business boomed. Meanwhile, I tried to suppress this thing between Doug and me. When Doug texted that he was moving to Boston for a big promotion, I agreed to meet him for a drink. I told my husband, with whom I share a very honest relationship, that I was going to see an ex for closure. But as soon as Doug and I laid eyes on each other, that dark connection was still there. He walked me to my car, and we kissed. Then he told me to take off my pants. I obeyed. We were right back in it. He left for Boston with his wife the next morning. And just like that, our long-distance, extramarital D/s relationship began.

With 500 miles between us, we're in contact over e-mail, text, and Skype. Because BDSM is about so much more than just sex, Doug can still be my Dom from afar, focusing more on psychological control. I'll text that I'm going for a run, and he'll tell me I can't. Over Skype, he'll watch me get close to orgasm and make me stop. Or he won't speak to me because, with the distance, it's one of the only ways I can feel the sting of his decision.

We know what we're doing isn't fair to our spouses, but fortunately for me, I'm able to be honest with my husband about Doug. We went through counseling a few years ago and agreed to have an open marriage. I love my husband — and I love having sex with him, but in an entirely different way. Doug is my dark and my husband is my light. For Doug, it's not that easy. His wife has no idea about this side of him.

Recently, I flew to Boston for a long weekend when Doug's wife was out of town. He arrived at my hotel and made me sit on my knees while he spanked me with his belt. Even though we have a safe word, I've never used it. In a D/s relationship, you need to trust another human being in ways that are rarely explored. A Dom is intoxicated by someone who is willing to trust him or her that much. A sub is intoxicated by the surrender — and not because he or she is weak. A sub is willing to go to a place many people do not, or cannot, go. The physical pain is just a small part of it. And surviving it, enduring it, is a feat. I know it's weird, but I feel like if I can do that, I can do anything.

I didn't tell any of my friends about Doug for nearly four years. I just didn't want to be judged. Eventually, I started revealing details when we'd talk about our sex lives. They couldn't believe that I liked being bossed around, that I allowed a man to hit me. I explained that in his normal life, Doug would never hurt a woman. He even donates to a battered-women's shelter! One day at lunch I showed my best friend some texts from Doug. She got really upset by the controlling things he wrote, like telling me what to wear to work. And when I revealed that he had a wife, she was totally disgusted. We'd been friends for 18 years and she had been my maid of honor, but we haven't talked in nearly a year.

Sometimes I feel like I'm someone's dirty little secret. Doug is now a full-on conservative businessman. He lives in a huge house in a fancy Boston suburb; he plays golf, flies planes, runs marathons. (As embarrassing as it is to admit, he's a lot like Christian Grey.) And he has the perfect Stepford-looking wife. But the truth is, I feel bad for him. I couldn't imagine leading a double life like he does. And I do feel guilty about his wife. Yet selfishly, my main concern is protecting him and our relationship.

I love that Fifty Shades of Grey has gotten women talking more honestly about their fantasies, but I hate that the book perpetuates the notion that a Dom must be messed up to be into this kind of sex. People who aren't in the BDSM world think that Doms and subs are broken people. Subs supposedly have no backbone, have daddy issues. I am completely alpha at home and work. I have two full-time employees and am a bossy boss. Subs are not doormats. We are just expressing darker sides of ourselves the way everyone else probably has some fetish they're afraid to share.

Last week, I got home from a weekend with Doug in Boston. I don't know how much longer we can go on with the distance and his sneaking around, but I can't imagine my life without Doug, without this in it. For now, I am comforted by the scenes I play over and over in my head. The way he walked into the room the last night and pinched me so hard that I inhaled deeply and tried not to cry out. "What should I do to you for making me wait?" he asked. "Anything you want," I answered. And I meant it.

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