Buffy Summers lived past her intended expiration date and didn't get to die a clean and perfect pure hero, she's not the same innocent and sunny girl she once was, she falters and is afraid and feels ugly feelings and has desires that she feels dirty for having and everyone around her (even when they love her) disappoint her and she disappoints them for not being perfect so when she has these ppl in her life that reflect and mirror these hidden anxieties and desires she is repulsed and terrified, ESPECIALLY when she sees the good in them bc it forces her to see the parts of herself that she hates and if she can love someone despite that, then that means she could potentially accept and integrate those same aspects of herself which is a terrifying prospect when most of your adolescence has been spent trying to hide that part of yourself from others who need and demand that you hold yourself to impossible standards at all times bc the fate of the world is literally on your shoulders.
She kills with kindness (gently kissing a comatose Faith, acknowledging Spike's humanity by calling him William when she breaks up with him) at the same time that she begs to not be forgiven. She cries when she realizes Spike got his soul for her and asks him in horror WHY he would do such a thing because it is literally agonizing for her to confront with such honesty that someone could change so fundamentally for her, make such a sacrifice for HER. She feels unworthy and Wrong and it is precisely through her ability to see the good in others and forgive them (something she's often condemned for by others!) that she proves her own Goodness and is able to begin to reach a place where she can forgive herself and break free of the vicious narrative that she and the Slayers before her have been shackled too. She believes in Spike, she works together with Faith again and acknowledges their shared right to the scythe, and she ends the series no longer alone. The same season where she breaks the cycle is the same where she learns the origin of the first Slayer, the same season where she tells Spike that she doesn't hate like she used to. Buffy's own darkness is an essential part of herself inextricably linked to her love and her greatest strengths as a hero, and she isn't free until she can acknowledge and accept that enough to be a hero of her own making, forging a better path for the girls who come after her and finding peace for those before her
