Girl, I wouldn't call them dumb. Nina is just too stuck with conventional dating ideas. Her dating experience has certainly colored her way of thinking, but she should try thinking outside the box: While buying clothes together for a more formal date can certainly be a date in itself, it only means they'll be having two dates (one informal and one formal) and I fail to see the problem here? The more dates the better, yeah? Even a routine shopping trip or a simple dinner together can be a date if both of them think it is! All that really matters is that they enjoy their time and get to know each other better.
So that's why Yuu was eager to play third wheel. She was trying to sneak away from studying...
RIP. Baseball guy Nozomi spilled his spaghetti and blurted it wrong so it's a crash and burn for him. Bro now has to beat the quickshot allegations. Back to the drawing board for you, but a rejection is a rejection. It certainly won't look good if he tries to keep pushing for another confession even after she already said no. His bad luck that he didn't intend to confess at this time, or did he?