Denial.

{if Shame > 74
}I can't! I just... I can't. It's too wrong, it's too much of a betrayal.
{elseif Shame > 50
}It's too risky! I'm going to get caught...and Brian will call off the wedding...I can't chance it...
{else
} I want to so badly....I need this... but I'm too scared. He's going to find out.... the risk is too great. She was surprised at her anger towards her own fiancee in that moment. {endif
}"I'm sorry. As good as it could be... I can't do it."
In an instant, Tim changed. He smiled, and set her on her feet. "No worries." His tone was completely different: no more dominance, no more intensity in his eyes. He had returned completely to just a normal guy, with no cares or judgments. "If you ever change your mind..." he handed her a card. "That's my private number."
Beth was a little taken aback by the whiplash of his sudden change, but then she realized that it made perfect sense. Tim wasn't Christian Grey, he was just a normal guy who was into kinky sex and being a dom. To him, it was just fun roleplay, and if she said "no, thanks" that was that. And iff he was willing to do that with a girl who had a fiancee? Well that made him no worse than a lot of guys, she supposed.
When Jake and Lindsay emerged from below, Lindsay was brazen and unashamed, and was giving Beth the most pleased look she had ever seen. She thinks she's had some kind of victory.
Jake looked a little more red-faced. He was clearly trying not to look like he had just been fucking Lindsay, despite her complete lack of doing any kind of disguising of that fact. As the time was rapidly approaching to head back to port, Jake and Tim swam back to the beach to start gathering things, leaving her alone with Lindsay.