Buffy: You and Willow are my best friends.
Xander: But Willow’s not looking to date you. Or if she is, she’s playing it pretty close to the chest.
A defining foreshadowy line.
At the end of the first season, the first gay joke was made. And it was about Willow. It was rumored very early on that Joss Whedon knew he was going to have a gay character on the show. And it was a toss up between Xander and Willow.
In the second season episode Phases, Xander gets a little squirrelly while the Scoobies are looking for possible werewolves. One of the suspects was Larry, who just so happened to be gay. He came out to Xander while being interrogated, making Xander extremely uncomfortable. That scene could have been very telling, if Joss had decided that Xander would be his colorful character.
In season three’s Dopplegangland there is another poke at Willow’s future gayness. Vamp Willow gives off a very touchy/feely vibe, to which Willow responds:
…And I think I’m kinda gay.
But it’s not until season four after Oz leaves that Willow takes a look at her life, steps back, and comes out to her friends. Everyone, the audience included, is shocked, but accepting. It’s a relief seeing Willow happy and Tara does that for her. After Oz left, she was left broken and crying. And Tara helped turn that around.
Willow, as a character, is intensely deep. In the beginning, to define the religious parameters, Willow was defined as Jewish, and established by her name “Rosenberg.” However, Willow’s religious orientation did little more than be poked fun at by saying things like “Tiny Jewish Santa” and having “big, honkin’ menorahs.” And by going to Xander’s house every year from Christmas to watch a Charlie Brown Christmas.
It was a crucial part of Willow’s character and her development for her to come out as gay and was equally important for the audience to see Willow in a successful romantic relationship with a girl. It not only defines her as an individual, but it creates a deeper, much more important story arc for her.
Had Willow not had a special relationship with Tara, maybe she wouldn’t have gone all black-haired and killed Warren after Tara’s death. Maybe she wouldn’t have developed so far, and maybe she would have remained a one-dimensional character. But in turn, she may have gotten worse with her magick addiction and the viewers would have seen a side of Willow that was more dangerous and evil than she was.
Tara gives Willow her humanity. She gives her life and purpose. Tara and their relationship give Willow essence and allow her to grow and give her reason to be.