Well, I think the song draws on both sexuality and security. The whole song represents a relationship, and how it changes as time goes by. At the start is just about sex, she feels young and gets the "tingles". The second stanza is similar, but she starts to feel safe in his presence. In the third she has fallen for him, and doesn't know what to say (hint: it's three words). By the fourth stanza, and the last rendition of the chorus, she is completely satisfied with being with him, even asleep. She now was him to take his time holding her tight.