If y/n wore high heels for their date, Itadori won't exactly be against it since it's her preference. But that doesn't mean he won't be worried. "Are you sure you will be okay with those heels?"
If y/n tells him, she will be fine, he will still continue to worry, but go on with their date. Not that he doesn't in daily basis, but he will make sure to stay within his arm length distance to her in case she trips or anything.
At one point, y/n trips as Itadori has anticipated. He quickly wrapped his arm around her torso and make sure she was stable on her feet. He then looked around for the nearest shoe store. "Y/n, I know you want to wear your heels and I do think they look amazing on you, but I think it will be better for you to get something comfortable. I don't want to see you hurt."
Although y/n was not happy with it, she nodded her head as her feet were hurting too much. Itadori smiled at her as he helped her with her new shoes. He then left a gentle peck on her forehead before letting out a chuckle. "Now that your feet are comfortable, I hope your attention will be on me now rather than your feet and enjoy our date better."
He said that just so he can make y/n feel better which obviously worked as she was now smiling. She admits her attention was on her feet since it began to hurt too quicker that she has anticipated. With her comfortable state, she certainly did enjoy her date better.