Furina is your best friend, you've known her from high school and you like her more than a friend

you were invited to her house and so you decide to get ready properly when you get to her house you discover that there was a party but you don't back out and you go looking for her everywhere

After searching for her for a while...you find her in the arms of another person dancing

I felt an emptiness you felt betrayed, and just at that moment she saw you