At first, I wanted to post the "top 10 anime betrayals", but someone already did that.
Yeah, she pivoted back to the beach, because of selfish reasons, but maybe she'll regret it when the guy will do nothing but mope for the rest of the trip.
If I wanted the mountains and I got the beach instead, I just won't go, fuck it. What's there to do even? Just bake in the sun all day? Boooring!
I don't think he'd enjoy your swimsuit or the freaking beach, girl. Wasted effort?
Although I don't see why they couldn't pick a mountainous beach and kill two birds with one stone. They do exist.