Okay, I’m not going to tell anyone how to think, but nobody can deny that Haruka’s life was so… dull before meeting Rin. Like, he was either apathetic, annoyed by whatever happened or trying to escape loneliness by using the water. If he thought something was troublesome, he just avoided it. He was following a routine, with nothing that made his days more interesting.
But then Rin comes; lively, cheerful, pushy annoying Rin who knows what he wants and doesn’t mind if it’s difficult, because he’s going to get it. And what he wants is Nanase to swim in the relay with him, and if Haruka says he won’t Rin doesn’t mind because has had his eyes on him for a long time and isn’t going to give up without trying with his everything.
And of course at first Haruka thinks it’s troublesome and wants to avoid the whole relay thing. But Rin isn’t Makoto or Aki and he’s going to find a way to convince him. And Haruka has never felt so much annoyance; hell, Haruka didn’t even know he could get this annoyed until that ridiculous airhead came to his school to mess his life up.
And the worst thing is, Haruka knows nearly since the beginning that Rin has won. And that’s what annoys him the most. He’s almost until the end in denial, because he doesn’t want to admit that it’s not annoyance anymore. He agrees to swim in the relay. He gets more aware of the people surrounding him, he gets curious, he gets more alive.
But then Rin says he’ll go to Australia. And how dares he. How dares he make this mess Haruka doesn’t even know how to deal with and leave without batting an eyelid. Better get back to the water- oh, wait, Haru, dear, isn’t it running away? But Haruka never runs away… well, maybe a bit. Maybe a little more than a bit. But he’s not going to do it anymore, and that’s what matter.
And they swim the relay and it’s amazing and they make a promise when they bury their trophy, and Rin leaves, and Haruka doesn’t want to admit he misses such a troublesome guy so he hides behind a childish resentment.
But what matters is that the damage is already done. Rin has changed his world for good and Haru can’t and doesn’t want to get back to what he was before because he absolutely loved the relay, loved swimming with everyone and loved the sight (and the lesson) Rin showed them all.