Who was the real fool for love in the relationship between Spike and Drusilla?
Many say it was Spike, especially since Drusilla had cheated on him with Angelus during late Season 2, and eventually dumped him for good in South America.
My answer? I think it was Drusilla.
I believe that Drusilla loved Spike a lot more than many realized. I also believed that the main reason she cheated with Angelus in the first place was to make Spike jealous, because she feared that the peroxide vamp was developing feelings for Buffy.
Drusilla may have seen signs of Spike's feelings toward Buffy in episodes like "Halloween", when he seemed preoccupied with studying the Slayer's fighting moves and in "What's My Line? - Part 2", Spike's words before his confrontation with Buffy seemed to hint that he was looking forward to more than just fighting the Slayer. And Drusilla had witnessed that moment.
I think the scene in "What's My Line - Part 2" had finally led Drusilla to resort to the jealousy game, especially after Angelus had resumed control of the family. But that all blew up in her face, when Drusilla's infidelity led Spike to form an alliance with Buffy in "Becoming, Part 2". Poor Drusilla. Can you imagine how she must have felt when she realized that her love had formed an alliance with Buffy, of all people, to betray her and Angelus?
For quite a while, I had believed that she genuinely preferred Angelus over Spike, until I saw that scene from "Fool For Love":
DRUSILLA: Why can't you kill her?
SPIKE: You're the one who keeps bringing her up!
TITLE CARD: South America, 1998
SPIKE: I haven't said a word about the bloody Slayer since we left California. She's on the other side of the planet, Dru!
DRUSILLA: But you're lying! I can still see her floating all around you, laughing. Why? Why won't you push her away?
SPIKE: But I did, pet. I did it for you. You keep punishing me. Carrying on with creatures like this.
CHAOS DEMON: Okay, you guys obviously have a thing going on here.
DRUSILLA: I have to find my pleasures, Spike. You taste like ashes.
SPIKE: (re: demon) So this is my fault now?
CHAOS DEMON: (to Spike) I didn't know she was seeing somebody. (off Spike's look) I should take off.
SPIKE: Yeah, why don't you do that?
The demon blows a kiss to Drusilla, then walks off.
DRUSILLA: You can't blame the ghoul, Spike. You're all covered with her. I look at you... all I see is the Slayer.
Hmmm. I guess she had figured it was best to dump Spike, before she could endure the humiliating experience of being rejected by him. Unfortunately for Drusilla, it was not meant to be. For in the end, Spike did reject her for Buffy - and right in front of the Slayer in "Crush". Poor Drusilla.