Which pain?

She hears his breathing. Deep, heavy and rhythmic. He turns and pulls her closer to him, spooning her from the back. He continues sleeping.
She felt his manhood, solid and sturdy, rubbing unconsciously on her back. She moves her hand over it and touches it apprehensively with one finger. It is rock-hard indeed. She smiles, while still keeping her eyes closed and continues gently rubbing it with her finger.
He moves over to whisper in her ears.
She wakes up.
She wakes up enough to know she was not in his arms. And all she had been rubbing was the cold, hard wall next to her bed.
She sits up and inhales deeply.
As she exhales, she slams her fist into the wall. A dull crack swept through the quiet of the room.
She looks at her knuckles, blood oozing from where her skin broke.
Better this pain, then the pain of frustration, she thought.