Rin Itoshi thrived in football as much as his brother did.
He liked to think of himself as uninterested in everything else, because the only thing worth his attention was football and its derivatives, only the things that would help him reach out towards finally grabbing the star that was meant to be his own; a path he chose for himself since the early ages of his life.
Football was a priority to him.
And then he met you. Whatever you did to him he was past the point of caring. Dating you hadn't been in his life plan, he hadn't meant to date anyone, but like water you slipped through the cracks of his walls and without knowing you had drowned him in you; and he wasn't desperate to go back to the surface and gasp for air.
He knew it, he was painfully aware that he may not be the best boyfriend ever in the world, but he was selfish and he couldn't stomach the thought of you leaving and being with someone else. So he improved himself because even if there could be better outside, he still wanted you to have something good with him.
Football was a priority, still his life in a way that he wouldn't ever give up, but so were you; and you didn't mattered any less than it. Soccer and you were equal parts of his life he wanted to preserve, and he wanted you to feel loved as much as he loved soccer.