I can pinpoint the exact moment my life split into before and after. It wasn't the first time Marcus kissed me in the supply room, or even the first time I kissed him back. It was three months ago, on a Tuesday that felt like any other Tuesday, when he looked at me with those desperate green eyes and said, "Just one night, Sara. Give me one night, and I'll never ask again." I should have said no. God, I should have said no. But I didn't, and now I'm standing in our downtown office at seven-thirty in the morning, watching Marcus walk toward my desk with two cups of coffee, and my stomach twists with that familiar cocktail of guilt and anticipation that's become my constant companion. "Morning, beautiful," he says quietly, setting the cup on my desk. His fingers brush mine, and even that small touch sends electricity through my nervous system. "Devon working late again tonight?" I nod, hating how easily the words come now. "Hospital shift. Won't be home until midnight." Marcus's smile is slow and knowing. "My place at eight?" "Marcus—" "I know, I know. You said last week was the last time." He leans against my cubicle wall, looking unfairly handsome in his navy suit. "You say that every time, Sara. But you always come back." Because he's right. That's the worst part—he's absolutely right. It started six months ago when Devon and I moved in together. Devon, my partner of three years, who works doubles at the hospital to save for our future. Devon, who leaves me notes on the bathroom mirror and still holds my hand during movies. Devon, who trusts me completely. Devon, who has no idea I'm sleeping with my coworker. Marcus joined our marketing team in January, all charm and confidence and attention that made me feel seen in a way I hadn't felt in months. Devon's hospital schedule meant lonely nights, canceled dinners, and conversations reduced to exhausted mumbles before sleep. I told myself I was fine with it. That's what you do when you love someone—you support their career, you understand the sacrifices. But understanding didn't make me less lonely. "Earth to Sara." Marcus waves a hand in front of my face, grinning. "You're thinking too much again. That's always been your problem." "My problem is that I have a conscience," I shoot back, but there's no heat in it. "Had a conscience," he corrects, and the casual cruelty of it stings because it's true. The Sara from six months ago would never have done this. That Sara believed in loyalty, in the sanctity of commitment, in being the kind of person who kept their promises. This Sara, though? This Sara has been meeting Marcus in hotel rooms and his apartment and once, memorably, in his car in the parking garage after the company holiday party. This Sara has become an expert at lying, at covering tracks, at compartmentalizing guilt into a box she only opens at three in the morning when Devon's sleeping beside her and the weight of what she's done feels like it might crush her chest. "I need to work," I say, turning to my computer. Marcus doesn't move. "Eight o'clock, Sara. I'll order Thai food. Your favorite." He walks away before I can respond, and I'm left staring at my screen, seeing nothing but my own reflection in the black monitor. I look the same as I always have—brown hair pulled back in a ponytail, minimal makeup, the same silver earrings Devon gave me for my birthday. But I know the truth. I'm not the same person at all. My phone buzzes. A text from Devon: *Morning love! Just finished rounds. Thinking about you. Can't wait to come home tonight. Maybe we can actually have breakfast together tomorrow? I miss you.* The guilt crashes over me in waves. Devon misses me. Devon, who's working themselves to exhaustion, who's building a future for us, who comes home smelling like antiseptic and still kisses me like I'm precious. I type back: *Miss you too. Breakfast sounds perfect. Love you.* It's not even a lie. I do love Devon. That's what makes this so much worse. "Sara?" My boss, Jennifer, appears at my cubicle. "Can you and Marcus present the Morrison campaign together at Friday's meeting? I think your collaborative energy really sells the concept." Collaborative energy. If she only knew. "Of course," I manage. The day drags on in a blur of emails and meetings and stolen glances across the office. Marcus catches my eye during the two o'clock conference call and mouths "tonight" at me. I should shake my head. I should mouth back "no" or "we're done" or "this has to stop." Instead, I nod. At five-thirty, I text Devon that I'm having drinks with coworkers and will be home late. Another lie to add to the mountain I've built. Devon responds with a thumbs up and a heart emoji, so trusting it makes me want to scream. At seven-forty-five, I'm standing outside Marcus's apartment building, my hand hovering over the buzzer. I could leave. I could turn around, go home, end this before it destroys everything. I could be the person Devon thinks I am. But I don't leave. I never do. Marcus opens the door in jeans and a t-shirt, hair still damp from the shower, and he pulls me inside without a word. His mouth finds mine, and for a few blissful moments, I don't think about Devon or guilt or consequences. I just feel wanted, desired, seen. "I thought you might not come," Marcus murmurs against my neck. "I shouldn't have." "But you did." He pulls back to look at me, and there's something in his expression I haven't seen before. Something that looks almost like tenderness. "Sara, we need to talk." Those four words send ice through my veins. "About what?" "About this. About us." He takes my hand, leading me to the couch. "I know we said this was just physical, just something fun, but—" "Don't." I pull my hand away. "Don't do this, Marcus." "I'm falling for you," he says simply. "I think I have been since the beginning. And I think you feel the same way." "I have a partner." "Who's never around. Who doesn't make you feel the way I do." He moves closer. "Leave Devon. Be with me for real. No more hiding, no more guilt. Just us." The request hangs in the air between us, impossible and tempting and terrifying all at once. "I can't," I whisper. "You mean you won't." "It's the same thing." Marcus's jaw tightens. "So what? You're just going to keep stringing us both along? Keep lying to Devon, keep using me for sex whenever you're lonely?" "Using you?" The accusation stings. "You're the one who started this! You're the one who said 'just one night'!" "And you're the one who kept coming back!" He stands, pacing. "I'm done being your dirty secret, Sara. Choose. Me or Devon. But you have to choose."