Maybe my view is different because I'm with Spike, I don't think Buffy didn't love him. I think she DID, but she didn't want to for weird and obscure reasons that just make her Buffy.
Granted, I could be tainted by the fact that I adore Spike and Buffy was never one of my favorite characters.
Buffy always has this black and white way of looking at the world that doesn't work well in the real world and also doesn't work in her world. One where she's allowed to screw up and make mistakes, but the people around her shouldn't. She gets so miffed at Xander and Willow, even when they just didn't tell her that Angel asked them to look into the whole Ford thing in Season 2. She gets mad at Giles for not telling her about his past in "The Dark Age". She gets all upset at Jenny because of not telling her what she didn't even know about Angel and the curse. But, she can just up and LEAVE when her Mother doesn't deal well with the Slayer thing and act like a brat when she comes back and people are ticked. And lies when Angel comes back.
And this just GROWS for season upon season.
She was always so black and white about Angel too. Personally, I'd have been looking for the curse from Day ONE when he turned bad and certainly would have been looking for a patch for that loophole too. But, NOOOO.
I think Spike gave her what she wanted. He was good at giving space and not pushing when he knew he shouldn't. He was supportive and, even with her protests, he seemed to know what she wanted and needed.
You can't say that by Season 6...this wasn't a girl that needed SERIOUS THERAPY. World ending, aside, more therapy than Willow and/or Amy and maybe even Warren. There is a reason she let Spike in, and that was because he understood. That and he was the only one she felt like she could show she wasn't always "Miss I Do Everything Right" to. Not REALLY the only one, but in BUFFY'S mind, the only one.
I suppose I can see that, in a way. There are certainly things I would tell my friends that I wouldn't want to bop into the kid's school and tell their teachers. But, Buffy's issues were a BIT overblown. She seemed to WANT to see herself a certain way, Dawn a certain way, be totally blind to Willow's issues, and wanted to see Spike in one way...mostly being "EVIL" and looking past anything he'd ever done that was "good".
Personally, I think she DID love him...she just wouldn't admit it because she's a bit of a mental case and he didn't fit in her black and white world.
Maybe that's why I like the season so much. Because it's like it all hits the fan. While Buffy's not paying attention and not being honest about her insecurities about herself and refusing to see that not everyone is either all good or all evil, Xander's relationship goes down the toilet, Anya goes back to being a demon, Willow loses Tara, then goes absolutely nuts, and Buffy's not even on top of things to realize that maybe Warren should be at the TOP of her radar because he's actually insane.
I think the season is EXTREMELY representative of real life...minus she demons. It's some serious insight into what happens when you aren't honest with yourself and get so wrapped up in hiding your feelings that you're then blind to the world around you. Something Buffy, Willow, Xander and even Dawn are all guilty of in this season. It's a season about being honest and realizing your own faults. If they had, Buffy might have realized that Spike wasn't really "bad", that she wasn't supposed to be all perfect and strong all the time. Willow would have listened to Tara and eased off the magic. Xander would have been honest and talked to Anya about his feelings before the wedding. Dawn wouldn't have felt so ignored and started stealing. And Spike may have realized earlier that a soul might be a plan.
And, whether it ends up being a favorite of yours or not, I think it was necessary for the series to make it to season 7....and further.