He takes over.

"Get your hands behind your back. Clearly, you need someone to show you." She didn't hesitate to obey, entranced by his dominance. She tried to keep quiet as she felt rope being coiled around her wrists. Oh...yyyyyessss.....
"Can you feel your fingers? Wiggle them for me." She nodded, and obliged the wiggle. "Good." She was then spun around and pressed with her back against the door of the bedroom cabin. She couldn't see the sex anymore, but now she was staring into Tim's intense gaze. It was mesmerizing as he pulled her bikini bottoms off and spread her knees, before commencing to finger her pussy with two fingers, with his other hand tight on her neck. She could have screamed as the fingers hammered at her spot from the inside, as his thumb flicked her clit on the outside.
"This is better, isn't it?" his voice was still exhilarating as he pressed close to her body. His fingers were building a strange sensation in her pussy and all throughout her nether regions.
"That....feels...different.."
"Of course it does, you bad girl. You weren't doing it right."
A couple of seconds later, she felt a strange surge...it was an orgasm, but...she gasped as a fountain of fluid sprayed out of her pussy, soaking Tim's body and hers. I...squirted?! I've never...in my life.
"That's good, baby." Tim whispered smoothly in her ear. It was more than Beth could process. Her eyes rolled up and she slipped into a state of semi-conscious bliss. The next thing she knew, her hands were untied and she was being cradled in Tim's lap, in the enclosed dining area of the boat. Her bikini was piled on the bench next to them and Tim was stroking her hair.
"Welcome back."
"Why...why did you do this?"
"Lindsay told me... you crave... this kind of interaction, and that you don't get it. And, she told me your needs have been shamefully neglected. I wanted to help." God... why does that make me furious... AND turn me on so much?
"I... I've made a big mistake... I'm supposed to be getting married in four months."
"That hasn't changed, Beth."
"But..."
"You need something your fiancee can't...or won't...or just isn't, giving you." His tone faded back into a dominant one. "You are a wayward, willful, sexually wild little girl who needs correction, and domination. Tell me the truth... don't you really want this?" His eyes dared her to tell him he was wrong.