This is what happens daily. Don't hide your feelings. When you get the chance, get to know them! They will eventually know why.
This just happened to two of my friends. One of my friends was struggling to ask someone out. The other one that she liked was also my friend. She likes him but he doesn't know. He likes her, but she doesn't know. They both got to know each other and are now together. Don't hide your feelings.
