Tara is not only much more centered, but I think she's more experienced with bad relationships and interpersonal disasters. Willow doesn't know how to handle it when things fall apart not with the monster of the week but with a lack of trust.

And Xander, even if he got to see more dysfunction with his folks, really isn't any better. He fumbled through his relationship with Anya, he bumbled through the clothing fluke and he pretty much tripped his way through any date he had with Cordelia. Those two are not helping each other.

So Xander does need to find people who can help him, and I have to say, Willow is not on the top of that list. Sadly, right now, Spike is not on the top of that list either.