Good point whoever said about it being unfair that Buffy made fun of them for trying to slay in her place. Could have been maybe an opportunity to explore Buffy maybe forgetting she's different from other people? Like, Buffy just kinda figured everyone would bounce right back from their injuries because she does? I dunno, "Buffy, the rest of us don't have Slayer healing. We spent the summer recovering from our injuries because normal people need time," and, "Oh, sorry if our slaying is lame to you, we don't have super strength and half of us just got outta the hospital so,"

But it's not just the physical injury part of it? Like Buffy's friends' trauma, like, emotionally (especially Giles', but also Willow) was kinda almost just as bad as Buffy's but they still stuck around and fought?

I think it was totally valid for Buffy to leave. She's just a kid, she's not being paid, she doesn't have to stick around to do that job. But doing it while her friends were so gravely injured is kinda a dick move. Especially when her martyr complex kinda got them hurt in the first place, running off to fight Angel alone. She could have at least kept in touch. But Will and Xander handled it probably the worst any person could handle anything so.