Love Story: A guy promised his girlfriend

A guy promised his girlfriend that he will sing in her 18th birthday..
..
Her girlfriend was so excited because she never heard him sing
before. Never..
..
She marked the calendar.
One month before her birthday, her boyfriend died in a car accident..
..
She cried and forget everything even her birthday.
She threw away the calendar and stayed at home.
Without any idea of the date, at 12 midnight as she was sleeping so
deeply....She was awakened by a kiss of a cold wind.
She stood up and heard someone singing a song..
She was shocked because the song is their THEME SONG.
and later on the cold wind whispered.
"Sorry if I'm out of tune babe.
Happy Birthday... I Love You..."