I'm currently watching Buffy: Season 5 (just finished disc 5). Based on the travesties of Seasons 6 & 7, I'd forgotten that Season 5 is actually, well, pretty good.
It doesn't have as many classic episodes as the other seasons. Despite its weaknesses, Season 4 has at least three classics: "Pangs," "Something Blue," and "Hush" (oh, and "Superstar"). Season 5 really only has one: "The Body." I like "Intervention" personally, but I don't think it has that quality, the quality that makes one remember an episode for itself, rather than the story arc it belonged to.
Having said that, I do think Season 5 is well-written. It has a consistency about it that Season 4 lacks (and I'm not even going to get into Seasons 6 & 7!). If I remember correctly, there was a strong chance Buffy would be cancelled after Season 5, and the writers made a real effort to create a big, Buffy-worthy send-off.
Which brings us to the handling of Buffy & Riley. I was very impressed by the break-up writing for Buffy & Riley. Compared to the break-up writing for Anya and Xander--okay, I said I wouldn't get into the last two seasons. In any case, Buffy & Riley are handled extremely well. I found their break-up entirely believable and, even, inevitable.
To be clear, I am not one who loathed Riley. I am also not one who takes sides on the Buffy & Angel v. Buffy & Spike debate (except to say, I think Buffy & Spike were handled very badly in . . . OKAY, I WON'T mention the last two seasons). I actually quite like Riley. But he and Buffy would never have worked and even though Buffy went running after him, I think it's just as well Riley missed her.
Riley needs to be needed. Now, to an extent, we all need to be needed re: Xander's "comfortadore." But Riley doesn't just need to be needed in a Maslow's heirarchy kind of way, Riley needs to be needed in a "define me" way.
That is, Riley needs someone to tell him how to be needed; for another type of gal, that would work fine, but Buffy, for all her self-reliance, is not into managing her relationships. And her relationship with Spike points the distinction.
Spike is the ultimate romantic; even when he was William, his relationships with all women (including, we later learn, his mother) are founded on emotional highs. This isn't the same thing as chivalry by the way--that's Angel's gig. But Spike defines moments around him in terms of desire, lustful, affectionate, and fanciful. This makes Spike easier to control than Angelus (bad Angel) since Spike is willing to sacrific dreams of revenge for good onion rings. This also makes Spike (and I quote him), "Love's bitch," but, and herein lies the lesson, this is Spike's nature.
Spike isn't waiting for someone to define him. He's already defined. When he decides to love Buffy or rather when he decides that loving Buffy is inevitable, he goes at loving her (or stalking her) with all of himself. He doesn't wait around for Buffy's signals. He doesn't even wait around to see if she approves, and her lack of approval doesn't alter Spike's fundamental personality in the slightest.
Riley, however, needs the signals. He needs to be given definitions after which he is fine. This is one reason Riley becomes much more interesting once he re-enters the military. The military gives him definition. Now, there's an "every authoritarian institution is bad" theme going on in the last three seasons of Buffy which, other than being rather adolescent, also crippled a number of possible plot lines; I don't think the military MADE Riley want definitions; I think Riley is attracted to institutions that give him definition. There's nothing bad about that, and I respect Riley for recognizing it and going off to a life that will ultimately give him more comfort than Buffy can.
This brings us to why I think the Buffy-Spike relationship had much greater potential than, ultimately, it was given. In the last two seasons, the writers gave rather facile excuses for not promoting the Buffy-Spike relationship such as, "But Spike is evil." Yeah, sure, but the show had a regrettable tendency (repeated at the end of Angel) to pick and choose when exactly to remember characters' evil sides. I maintain that Spike's quest for morality gives rise to much more difficult questions of free-will, goodness and evil than, perhaps, even Buffy writers could handle.
In any case, I don't rest my defense of Buffy-Spike on the quality of Spike's evil. I rest it on the level of comfort Buffy feels around Spike. I think this is the key to the relationship; I think, to an extent, it is the key to every workable relationship (on television and off it). From the beginning, Buffy has no problem talking to Spike, and Spike has little difficulty comprehending Buffy. They speak the same language. To an extent, they even think the same. Until Spike starts stalking Buffy, she keeps her home open to him. She yells at him and then asks him to watch her family. She stops by his crypt at every opportunity.
I'm not saying that Buffy is secretly in love with Spike. She isn't in Season 5; I'm not sure she ever is. But she feels comfortable around Spike. Spike is sure enough of his own personality to take Buffy as she is. In Season 1, Buffy says to Giles (concerning one-episode-boyfriend-Owen), "Five minutes in my world, and he would get himself killed." Buffy finds no comfort in people who need her for what she can give them, whether the "what" is excitement or definition. Instead, Buffy finds comfort in people who love her but don't need her and go on being themselves (Giles, Willow, Angel, Xander, and Spike: interestingly enough, this means that Buffy finds comfort in people who may, ultimately, leave. If she had told Riley she needed him, he would have stayed; she told Angel she needed him, and he still left--thus the risks of loving people who have their own definitions and agendas).
I believe this desire for comfort outweighs all other types of love. Lust comes and goes. Affection is a long-term investment. Comfort is what people truly seek: to feel comfortable, feel like one can relax. In some Maslow's heirarchy way, this is the kind of love everyone is seeking: this person gets me, this person talks my language, understands what I'm trying to say. And really, what Buffy needs isn't someone who needs her to need him but someone who gets her and doesn't fall to pieces as a result.