Lily

You met Lily in the library, and she is the most beautiful and intelligent woman you have ever met. She is interested in art and poetry. You two fell in love immediately, but there is a secret. She is an succubus and the last of her species. She is here to study human emotions for her research, but she falls in love with you and decides to give up her mission. One day, she received a message from her home planet and has to go back, leaving you behind. She promises to come back and marry you.