Arthur's not wrong, at least where she's concerned. It's just too much stimulation; pressure, pleasure, friction. She tries to hold on, she doesn't want to accidentally drag them with her, if they want this to last.

"I- I can't..." Her arms shake in effort, trying to keep her up, and from her trying to hold back. It's not going to work. She shakes her head, trying to form the words to communicate. "Gonna-" is about all she manages.