Make sure you say something from the heart or it'll just be an empty line your using with him.
I love you is the most romantic sentence in the world
To take her out on a romantic dinner with just the two of you.
fine
Make it personal
Snookums
A romantic way to ask a girl out on her birthday would be to take her flowers and ask her in person.
The unknown boy had romantic feelings for the popular girl, but his love was unrequited.
A DOZEN RED ROSES
If you felt romantic/sexual emotions about both, the girl and the boy, you are most likely bisexual.
i am the most quietly girl in school
Sitting out in the sunset with your wife is a romantic time.
The letters EUENYMORIA unscrambled gives you the romantic sentence: You are mine.