This is the main point of the song. It explains how a girl can't move on with the man she loved; that she love dearly but the one she love can't love her back; for the man himself is in love with someone else. So to mend her broken heart, she always fake a smile whenever he talks about the girl he love, but he is oblivious with the feelings of his friend towards him. For us, faking a smile is the best solution or the biggest step to move on with a broken heart.