I like my Buffy bisexual like me! Of course I am 55% lesbian, 45% hetero.
Buffy on the other hand seems straight but open minded, willing to try anything, and more about making a connection than trying to fit a mold or identify herself in a certain way. I mean, she HAS been with two vampires, one of which didn't have a soul when she started sleeping with him.
The writers say it is cannon that Faith was in love with Buffy. They wrote lesbian subtext to the Fuffy scenes. Eliza played the character being attracted to Buffy because the writers told her to but would go even farther with it and they never told her to reel Faith in.
That FE quote was "Deep down you always wanted Buffy to accept you, to LOVE you even. Why do you think that is?" And Faith gets flustered and says, "What are you, a shrink now?" I thought it was always very telling that one of the first things Faith does in Buffy's body is get naked and touch herself in the tub.
I could of easily seen Buffy and Faith getting together. I'm actually surprised it never happened. But then the networks would have NEVER allowed it. They couldn't even get that kiss on the lips in Enemies allowed and had to change it to the forehead. Fuffy kisses/sex would've been like Spuffy S6 mixed with the cemetary kisses and fangasm from the Bangel romance. Tara and Willow would've been blushing.
I completely believed Buffy would have sex twice with Satsu. That relationship was about the people involved and not about "being bicurious" or wanting the "lesbian, gay-type lovin". There was mutual respect, admiration, trust, comaderie, need, etc. Buffy needed to feel loved, needed the physical release that comes from sex, and wanted to pretend during the hours they were in bed together that she was in love when they both knew--even before they kissed--that she wasn't.
Buffy was always supportive of Willow being gay. She welcomed Tara into her life, gave Willow advice on the Oz-or-Tara situation, let her babysit Dawn, defended her to the Maclay men, invited her to her birthday parties, let her live in her house, smiled when she saw Tillow kissing and even gave them permission to forgoe Trio research so they could continue their sexathon.