Sakusa has wavy hair, which ends up being quite difficult to maintain. Products specifically for wavy hair are a bit expensive, and some are even downright bad, but in the end, he loves his hair; it's what sets him apart from other boys with plain, boring straight hair.
And you, as his girlfriend, understand his struggles, especially since you have curly/wavy hair yourself. Plus, your hair is much more unruly than Sakusa's. He always sees you stressing about your hair, having trouble detangling it. You didn't find it easy to like your hair, but you didn't want to change it, you thought it was part of your identity, until...
Some girls in your class started making mean comments about your hair, always pulling it between classes, making snide comments. "Do you even wash that?" "Your hair looks like steel wool!" "Your hair is terrible." These comments started to make you hate your hair. So one random day, you made a drastic decision. You straightened your beautiful curls, your hair now like a waterfall framing your face.
You showed up at school like this, and your poor boyfriend didn't even know anything; you didn't dare tell him. The girls in your class, however, didn't stop with their nasty comments, making them even worse.
And at lunchtime, when Sakusa finally saw what you had done to your hair, he held you firmly by the shoulders, not letting you look away.
"What the hell happened to your hair?"
He asked, his voice serious but tinged with concern.