Chouji wasn't sure about Ino at first. To start with, she was a girl, which made her an entirely different species and Chouji tended to side with Shikamaru in his opinion of women, having not met too many of them so far. They were troublesome, Ino, perhaps the most troublesome of the lot.
She was pretty enough to make Chouji feel uncomfortable and awkward around her, and a little bit ashamed of himself. And pushy...boy was she ever pushy
. She bossed all of them around, complained more than Shikamaru (and louder too), and everything had to go her way. She demanded constant attention and entertainment, and never took "no" or "I'm tired" for an answer. She bragged about herself too often to be modest, pointed out the flaws of others too readily to be sweet, and she was always commenting on Chouji's weight.
And then there was that entire year when all she talked about was Sasuke-kun this, and Sasuke-kun that, and how awful Sakura was to think she could keep the Uchiha all to herself, and on and on until Chouji wanted to stick a rice ball in her mouth just to give his poor ears a rest.
But then, when he was in the hospital being treated by Tsunade-sama, he remembered her bringing him fruit and flowers, sitting by his bedside and yelling at him for almost getting himself killed. And then she went and yelled at Shikamaru for being too wrapped up in his own guilt to visit Chouji, dragged him into the room by his ear, and made them both promise never to leave her behind again or she'd kick their asses from here to Wave Country.
And he remembered, after Asuma's death, Ino randomly showing up on his doorstep to demand that he help her ambush Shikamaru into taking a lunch break, or how she threw out every single pack of cigarettes she ever caught Shikamaru hording when Chouji couldn't bear to do it himself.
He remembered the look on her face when Asuma had made her promise to look after them both, and thought that, in her own way, Ino had been doing that all along. When things seemed to be falling apart, Ino kept them working as a team
, shoving their broken pieces together and keeping them there, whether they fit or not.
Chouji loves her for that, and always will.