When they'd gone to the gym today, they'd known very well that no serious sparring would take place. They were both safe and unharmed. There was no reason for it. That being said, she still expected some sparring to take place, playful or not.
It was a (sometimes unsettling) fact that she'd become familiar with over the last few years, though, that sometimes plans she made with Clint went entirely awry. It wasn't even always sex (even though it was usually sex) that made it happen - sometimes, her feelings for him just made her think differently than she would have before. The old, familiar part of her hated the idea of being that affected so much by another. The person she was now knew better.
She didn't protest the change of venue, kissing him slowly for a few more seconds before pulling away long enough to slide from underneath him. She respected the Avengers too much to let them walk in on she and Clint on someplace as communal as the mat. She wouldn't have let things get much farther, herself.
Natasha stood then, heading toward the showers. She didn't wait for him to follow, just straightened her sports bra and pants and headed toward the locker rooms. She knew he'd come.