Older (15+ years) movie blind girl kisses passion. goofy guy, main girl watches thru window

blind girl meets funny goofy guy at party and he thinks she can see him and so he does this stupid dance that is supposed to be suave to impress her, and then she's like, ah, I'm blind, and he feels silly but they hit it off....then later she's in a room - her bedroom? - and there is something on floor but she knows and he says "how did you know it was there" and she says "i put it there" and then as she's stepping by him he grabs her and starts kissing her very passionately, and this other girl, the main protagonist - her sister? - who's watching thru a window sees it, and while previously she had been feeling superior to this girl, she then she says to this other guy "i just saw the most romantic thing that'll ever happen in my life, and it happened to someone else" or something similar...