Well, maybe not Shaespeare, but classical mythology is better. I did read an online essay once comparing Spike & Buffy arc of season six (especially the end) to Psyche & Cupid/Eos that was very convincing.

It was all about Psyche betraying Cupid's trust (remember, with the "don't look at me at night" thing, and the candlewax) and then having to endure numerous tests to win back love, much the way that Spike had to endure his own trials, get his soul, and endure torture to be worthy of Buffy's affection again.