Anticipation.

He changed his mind 'cause of what happened just now, like, fear truly gripped the both of them, they thought they had been busted.

Yes, the confidence was there minutes ago that they wouldn't be caught when they visit the river. They just needed to glance at naked females, stimulate themselves, and leave without getting caught.

..But now, the confidence wasn't there anymore, Oliver was now afraid due to what happened seconds ago.

You know, a certain occurrence can suddenly change a person's mind regarding something...yes, that's exactly what happened to Oliver.

"You've changed your mind? Why?". Aiden inquired though he knew the reason why he changed his mind.

"Didn't you see what just happened? Isn't that enough to give a person warning alert? As for me, I'm not going again, but I'm not stopping you though, you can go if you want to,