Never
An hour later, they still lay together on the floor. House had put his jeans, but Cuddy was only wearing his shirt. She laid against his bare chest, fast asleep, as he twirled her hair around his finger, watching her sleep.
After a while, Cuddy woke up with a stretch. "What time is it?" She asked yawning.
"Quarter past six." He replied calmly.
"Six!" She exclaimed sitting up. "I should be getting here in 15 minutes."
"I've still got hours." House commented lazily. "And no one cares if I haven't had a shower and am wearing clothes from yesterday."
Cuddy groaned and laid back down. "Maybe I'll call in sick."
House grinned. "Maybe I'll call in sick too and we can spend the day in bed."
"No House," she said softly. "This is never happening again."
He stood up, pulled his undershirt back on, collected his shoes and cane, and limped our of her office without a word. She watched him go, tears welling in her eyes. After he disappeared she realized she still had on his button-down.
Three days later, she slept with Kevin. He was meek and submissive, just as House had observed. In her darkened bedroom she pretended his eyes were blue instead of brown and held more than just respect.
She and House avoided each other for weeks after that. They only spoke to each other when they had to. Anyone within the vicinity could feel the tension.
Cuddy figured the only person who found out anything was Wilson. One day while eating lunch in the cafeteria, he paused by her table. She glanced up at him, and the oncologist gave her a sad smile. Cuddy looked away, tears filling her eyes again. As she fled the room, she blindly bumped into someone. Muttering an apology she turned to go to her office when a hand grabbed her arm. She looked up to see House's concerned eyes studying her. As she turned again he dragged her down the hall to an empty exam room.
Once there, he locked the door, but left the light off. Cuddy began pacing the room. Finally she turned to him, "House, I'm sorry I hurt you. I never meant for any of this to happen..." He silenced her with a kiss. He pulled away, leaving her breathless, and walked from the room. From that day forward, it was as if nothing ever had happened.