A theme is a central idea of a story or passage. Whereas a universal theme is a theme of storytelling understood by everyone.
The power of love is universal theme because people enjoy romance, the idea of soulmates, and they want to find believe in an idea of a one true love for all of us. People can relate to love and is understood by most people.
Love has a strong impact and importance in literature. This emotion defines characters relationship with family, significant others, and even God.