Calvin and Hobbes
Watterson admits that Calvin and Susie have a bit of a wild crush on each other (Said by Calvin, "It's shameless the way we flirt."), and that Susie is inspired by the type of women Watterson himself finds attractive (which has led to speculation that Susie is based on Watterson's wife). Her relationship with Calvin, though, is frequently conflicted, and never really becomes sorted out, and the closest things are times when Calvin sends dead flowers and hate-mail as Valentine's Day gifts for his own enjoyment. (She feels he likes her enough to send her that gift, and he rejoices in her noticing.)