Because not every summer romance has a happy ending.
Usagi and Mamoru (Sailor Moon) - After Mamoru starts having dreams that his being with Usagi will eventually lead to her death, he dumps her. Even though he’s still in love with her, he continues pushing her away by being cruel to her every time they meet and pushes Usagi into binge eating (and even more whining than usual). Fortunately, this story has a happy ending: Mamoru discovers his bad dreams are really a trick and Usagi happily takes him back. Whew, we were pretty nervous for a minute there.
Hatsuharu “Haru” Sohma and Isuzu “Rin” Sohma (Fruits Basket) - Ah, the ol’ on-again-off-again. Though it seems like Haru and Rin are destined to be together from the time they even become interested in dating, they suffer their own trials and tribulations. After Rin breaks up with Haru (because she fears for his safety), Haru even goes so far as to wreck an entire classroom. Ouch. Thankfully, this story also has a happy ending and the two are reunited for good before the series’ end.
Nana “Hachi” Komatsu and Shoji (NANA) - NANA is one of those rare animes that pulls on your heartstrings fairly often, but Hachi’s break-up with Shoji (who *spoiler* cheats on her with a waitress) hits viewers hard. This story doesn’t have the same fairy tale ending Sailor Moon has – the lovers never reconcile, and they even agree not to see each other any more once they discover they may still have feelings for one another. Now, if you'll excuse us, someone must be chopping onions because our eyes are leaking.