Ask her to stop.

"Please stop, sweetie," you beg, cupping her jaw. "I don't want to cum yet."

Alex pops your cock from her mouth and has a cute frown. "So you want to fuck me?"

You nod a bit too excitedly.

She grins and turns off the water. "I guess you're hard enough now!" She stands up and you hold her hand as she steps out of the shower, making sure she does not slip. She grabs two towels and hands you one. You cannot help but gawk at her while she dries herself off, only to look away embarrassingly when she catches your stare.

"So where do you want to do the homework?" she asks, drying her hair. "The bedroom? Living room? Or even here?" She winks with a mischievous smirk.