You shouldn't tell someone they smell even if they do.
Marcie is at the beach with her boyfriend, who is sweating, and his underarms have a bad aroma.
Marcie doesn't want to have to smell her boyfriend's unpleasant scent.
Marcie suggests to her boyfriend they take a swim, so they jump into the ocean and play in the water.
Marcie tells her boyfriend he stinks and to get away from her, so he leaves the beach.
Her boyfriend is rinsed off from the saltwater and no longer has a sweat smell.
Her boyfriend decides he doesn't want to date a girl that treats him in that manner, and he dumps Marcie.