Yes. And she also discovers the identity of the visitor

Sarah had been so sure about herself not even an hour ago, full of confidence and energy. But the idea that her boyfriend could possibly reject her because of her unexpected and unreal transformation had really dampened her spirits. Still, she decided to be brave. There was no use to beat around the bush. She was a futanari now, a dickgirl with a massive cock. Even almost flaccid it was incredibly huge, thick and long, and her skintight black mini-dress kept it firmly in place in front of her stomach, its outline clearly visible out there for everybody to see. With no way to hide it, a retreat would only delay the inevitable.
Sooner or later she simply had to face her boyfriend, and other people as well. And so she used her spare keys to let herself in.

"Mark?"

Her question received no response.

"Mark?"

She tried again, even louder this time. Nothing.

Sarah looked in the kitchen, she checked the living room, but both were empty. However as she got closer to her boyfriend's room, Sarah began to hear something. Sounds. Voices. And what she heard soon left no doubt, that both Mark and his visitor were inside, and it also was clear as day what exactly they were doing. Sarah was surprised and shocked nonetheless: Sounds of sex, sounds of pleasure, grunting and moaning reached her ears. Her boyfriend was clearly cheating on her! And Sarah also recognized the other voice, she instantly knew who it belonged to.