John, on the last step before the landing, noted the bathroom door was slightly ajar, a wedge of light across his feet. He heard Kaitlyn's soft moan, the one she makes that drives him wild. He took another step, and through the gap, he saw her, back arched against the sink, the navy fabric of her dress pulled apart at the slit, which revealed her hips and panties pulled to one side. The stranger worked his fingers between her legs, his hand slow and gentle, his thumb pressed and circled her large erect clit. The wet sound his fingers made in her pussy reached John's ears, and his cock hardened against his thigh, thick and aching.

Kaitlyn's head fell back, dark hair brushing her shoulders, her mouth open. Gripping the edge of the sink, she pushed down onto his fingers. The stranger's other hand found her braless breast, fingers digging into the soft flesh. He leant in and said something low, too quiet for John to catch. Kaitlyn laughed. John's grip tightened on the banister. He should move and announce himself. Instead, he stayed, barely breathing, watching his wife take another man's fingers, at their friends' house party, while everyone laughed, drank, and enjoyed themselves downstairs.

Kaitlyn turned to face the mirror, bending over the sink. The stranger shifted as well, and Kaitlyn's eyes widened as his fingers entered her once more. John noted her panties pulled across her large, gorgeous ass. She looked into the mirror above the sink. John's heart beat hard in his chest. For a moment, there was nothing, just the dark sweep of her lashes against the glass. Opening her eyes, she saw him. Her body was still, but only for the slightest moment. She didn't look away. Holding his gaze in the reflection as her hips resumed their push against this stranger's fingers, a show of it now, deliberate from her to him through that single line of sight.

John felt the heat rise up his neck and into his cheeks. She knew, she'd always known, the drunken fantasies confessed. But here, in this brightly lit reflection, it's not a secret anymore. Her mouth shaped 'stay' for him to read, and her eyes stayed locked on his. The stranger fingered her harder and deeper, making her moan louder now, fogging the glass; she didn't flinch. Didn't break eye contact.

John remained in place, the party continued, distant laughter and clinking of glasses behind him, and all he could do was watch his wife watch him watch her. The mirror connected them, her flushed face, his shadowy figure in the hallway.

Kaitlyn's rhythm faltered like she'd lost power. Her hand left the sink, and her index finger pressed to her lips, but her eyes never left his in the mirror. Then she mouthed the word, slow and deliberate, 'Watch'. The command rang loud in John's ears even though it was no more than a whisper. John's breath caught in his chest; he was still motionless, his cock aching in his trousers.

The stranger hadn't noticed or didn't care. His fingers still worked inside her, matching her rhythm, and he murmured something against her ear, a question maybe, or praise. Kaitlyn didn't answer. Her focus was on the doorway, on the shadow, on the word she had just given him, like a test. John watched her tongue wet her lips, watched her chin dip once in a nod as if to say. Yes, I mean it.

The crowd downstairs laughs at something, a burst of sound that seems to come from all too close. John traced the length of his erection with his fingers as it throbbed along with his heartbeat. He should turn around. Walk back down. Get a drink. Pretend he never saw. But his feet don't move, and his eyes can't leave the mirror. He didn't move from where he was as she had told him, and he didn't want to disobey her.

In the reflection, Kaitlyn's hand dropped back to the sink. Her hips rolling, but it was different now. She was performing for him, her spine curved deeper, her mouth open wider, but her gaze never leaving his. She let out a low moan that traveled down the hallway past him, and her teeth left a mark in the lipstick of her lower lip, a promise or a taunt. John now gripped the head of his cock through his trousers.

The stranger felt the change in her before she made a sound, the way her thighs tensed, the way she held her breath. He used all his fingers now, pushed them deeper, pressed them up into that soft spot inside her, his thumb firmly pressed against her tight asshole, almost penetrating but never fully inserting. Kaitlyn's mouth now let a sound escape, nothing like the polite moans from before. Her hand flew back, fingers digging into an ass cheek, her nails leaving marks in her skin as she locked around his hand.

Her eyes never left John's in the mirror. She held him there, pinned in that light, as the first wave rolled through her. Her cunt clenched around the stranger's fingers, gripping and releasing, and a cry from her throat, his name, she says it like a confession, like she's giving it to him as much as she's taking this pleasure. Her ass bucks against a stranger's hand, grinding, her thighs trembling, and she doesn't look away, doesn't close her eyes, doesn't hide a single second of it from him.

The stranger said something else as his other hand left her breast and fumbled at his zipper. He pulled his cock out, long and with a large mushroom head, and he stroked himself twice before his own climax. The first hot jet of cum splashed over ass cheeks and panties. The second landed at her dripping pussy, white and thick against her dark lips. He kept pumping, milking himself, painting her, until there was nothing left, his breath deep and long.

Kaitlyn sagged forward against the counter, her forehead pressed against the cool glass, her cheeks flushed, dark hair sticking to her temple. Her panties hung ruined, soaked with a stranger's cum and her own wetness, now covered in the evidence of what she'd done caught on the black cotton. She didn't move to fix them. Didn't reach to correct her dress. She just breathed, deep and shuddered, her eyes again finding John's in the glass.

The silence stretched. The stranger tucked himself away. He glanced toward the door, and his smirk caught John's shadow still on the landing. John didn't see him. John saw only his wife, her gaze steady, her lips pursed, her hand lifting slowly to press two fingers to her mouth, then extending them toward him in the mirror, a kiss blown through the glass, an offering. His cock throbbed, and the banister creaked under his grip. Downstairs, something breaks, and everyone cheers, and John still does not move, still doesn't know if he's going to walk forward or walk away.

Kaitlyn's hand found his, her fingers hot and sweaty, but with a confident grip. She pulled him back down the stairs, out of the light, and John's feet obeyed. Her dress brushed against his trousers as she passed, the scent of her, of her sex and that stranger's cum, rising from the fabric. She didn't look back at the bathroom. Didn't check if a stranger watched. She just led him down the stairs, her thumb pressed against his wrist like she was feeling his heartbeat.

The rush of the party hit them both once more: laughter, clinking glasses, someone's loud crappy story about something or other. Kaitlyn navigated the crowd. Her shoulder brushed against others, her hand still wrapped around his. John felt every eye that glanced their way; no one had seen what he saw in that mirror. She pulled him past the living room, past the kitchen island littered with empty bottles, and into the quiet of the back garden via the patio door. The music was muffled now, a low thrum through the walls.

She stopped and turned to face him. The dim light, the flush still in her cheeks, the smeared lipstick and mascara at the corner of her mouth and eye from the mirror. She didn't fix it or smooth her dress or check her hair. She just looked at him, her blue eyes bright and sexy, and her lips wearing, not quite a smile.

"Did you enjoy the show?" Her voice was quiet, a dare. She released his hand, and John felt the heat from his own body well up. Her fingers traced the edge of his shirt collar, slow, and she watched his face the same way she watched him in the mirror, like she was reading every thought before he could form it.

John croaked as he tried to speak. Kaitlyn unzipped him and dropped to her knees, taking him into her mouth. He was too big to deepthroat, she knew from past experience, but she tried anyway for him now, and with all the excitement, he didn't last but a moment, but what a moment it was.