He gives her a ride, and tries to take some power out of this

It took almost half a minute for Tom to reply, long enough that Sarah was ready to hang up waiting for him. When he did speak, she could hear the tempest of emotions inside of him. Anger, resentment, jealousy, and excitement. Such a wonderful cocktail to hear in a man's voice. "What's the address?" She gave it, and all he said after that was, "I'll be there as soon as I can."

Sure enough, under ten minutes later he was there, pulling up in his car, looking miserable. Seeing that gave Sarah a rush of power. She'd cuckolded this idiot, she'd ensured his wife would be tainted forever, and he still showed up for her. It would be sweet if it wasn't so utterly pathetic. "Good boy," she told him as she entered the car, in the same tone that one would speak to a dog who'd just performed a trick.

And then...then Tom surprised her.

The man turned the key in the ignition the wrong way, and pulled the keys out of the car. "We need to talk..." he started, sounding like a man about to face a firing squad.

"What is there to talk about?" she asked, unsure what exactly he was trying. "You heard me over the phone, you know where I've spent my evening. There's no mystery here. Your wish backfired."

Gritting his teeth, Tom nodded. "That's true. I should have phrased this wish more carefully."

"Well, it doesn't really matter what you 'should' have done, now does it?" Starting to get annoyed by the judgy look on his face, she scowled and told him, "Go ahead, start the car again and get us back to your home. Once midnight is over, you can complain to your wife all you like. Of course, even when you do, she won't be able to regret it too much, now will she?"

"You're right there too. I realized that earlier today. I don't know if, when you change back into the real Sarah, she'll just be unable to feel shame about what you've done, or if her personality will twist to make it fit better." She didn't know either, and frankly, she didn't particularly care. "The thing is...you're wrong about there being nothing I can do." Horror dawning on Sarah, he held up the coin. "After all, I still have this. I should be able to just undo the wish about how she'll feel about it."

Mind starting to race, Sarah realized that perhaps Professor Saunders wasn't entirely the limp-dicked loser she'd thought him to be. "A-are you saying you want your wife to feel negative emotions? You want to actually make a wish that will hurt her? You are a truly terrible husband, aren't you?" It was a poor attack, and she knew it, but she didn't know what else to try.

"Maybe I am. But I can deal with that later. For now, I'm going to fix my earlier mistake." He opened his mouth to start the wish, and Sarah realized time was running out to stop him...but how?