Episode 7 of Season One - called "Angel" - revolves around the growing love between Buffy and Angelus and they have their first kiss! But then Angel turns into a Vamp and has to jump out the window. Truly a classic Beauty and the Beast moment.
Later Buffy thinks that Angel has bitten her mother, Joyce, when really he was saving her from the evil Darla, his sire, who has been helping The Master. This leads to a dilemma as Buffy vacilates between loving Angel and wanting to stake him. In the end, he explains that the Romany Gypsies have cursed him with a soul and while he wants to continue biting people and drinking their blood, he is so full of remorse that he never does.
The song "I'll remember you" by Sophie Zelmani, plays at the Bronze as Buffy and Angel say goodbye - but of course this is only the beginning of their long complicated relationship.
Sophie Zelmani Official Site