One may fall in love with many people during the lifetime. When you finally get your own happiness, you will understand the previous sadness is kind of treasure, which makes you better to hold and cherish the people you love
How can it be a happy ending story?? Where is the human princess? Things won't be so easy. The prince will choose a princess, not a mermaid. And where is her pursuit for the real soul? Anyway, true love conquers all.