Distraction.

Beth sucked and stroked Brian's cock for a few minutes, until he insisted the go upstairs to avoid waking Kyle. She blew him some more in the bedroom, and then they stripped out of their clothes to have sex. She put her face in the pillows and put her ass in the air. "Fuck me, baby." Brian liked to fuck her doggystyle, and she liked being fucked that way. As the sex continued, however, she realized that she was happy for that preference for a different reason.
"I love you, Brian."
"I fucking love you too, baby." She was glad that he didn't detect the hollow nature of her words. She couldn't stop thinking about Denny. While her fiancee worked his cock in her wayward pussy, she stared into the darkness of the bedroom and pictured her ex-boyfriend.
"Harder...please...." Brian picked up speed and intensity, but it was no use. She couldn't get Denny out of her head, and images of what could have happened that night wouldn't go away.

Please...punish me, baby. She could never say the words out loud, never explain. She wanted him to own her...to blot out her unfaithful thoughts. She tried to lose herself in the rhythm. It wasn't working, and eventually, when Brian came, she had to **** herself to lie with him and smile.
"Are you okay, baby?"
"Of course. Thank you for the good sex..." she kissed his cheek. He fell asleep soon after, clearly pleased with the state of their love life. She laid awake for a while, worried about the undisclosed desires she had for Denny. Sleep was a long time in coming, and dreams about her ex filled it when it did.