love stinks: why can't anyone be happy in the buffyverse?

BUFFY: It's just ... I just wanna know that there's gonna be another good one. One that I won't chase away.

XANDER: There will be. Promise. He's out there, he could come along any minute.

BUFFY: Yeah, and the minute after that I can terrify him with my alarming strength and remarkable self-involvement.

XANDER: What? I don't think you're like that.

BUFFY: Maybe I could change. You know, I could, I could work harder. I could spend less time slaying, I could laugh at his jokes, I mean, men like that, right, the, the joke-laughing-at?

XANDER: Or maybe you could just be Buffy, he'll see your amazing heart, and he'll fall in love with you.

--"I Was Made to Love You" (season 5)

The thing is...even though someone else is in love with her (and she with him, but I think she's in denial about it) (I'm not name dropping for those who don't want to be spoiled...) there's no happily ever after for Buffy by the time we get to season 7. Now, I can see the reasoning behind it...but my problem is this, Joss: WHY CAN'T ANYONE IN ANY OF YOUR DAMN SHOWS FIND LOVE THAT WORKS OUT??

Ok, now that I've yelled, I feel a little better. But honestly...why don't any of the relationships work out? I mean they either leave (Oz) (someone whose name rhymes with Smiley in season 5) , die (Angel in season 2...or someone else in season 6..."your shirt..."), and so on and so forth. Now I know in REAL LIFE (I really know this as well as the next person) that relationships don't always work out. I've seen it in my life and in the lives of others. But on tv...would it really hurt? I mean at least ONE person, Joss. ONE. I need some hope here. I'm with Buffy--I just want to know that there will be one I won't chase away.