When I was in h.s., my dad worked with Mercedes Lackey at her day job. After he begged me for a while, I let him give her some of my work. It came back dripping red. I was DEVASTATED and it was a serious negative impact on my writing confidence for decades afterwards.
I have since learned that the art of critiquing without devastating is a delicate, rare talent. It does NOT mean pointing out the flaws. It means helping the writer see how they can make their story better, to inspire and motivate. For instance, instead of “you keep changing point of view. This is confusing,” you might say something like, “I really like this aspect of the story, but I’m having trouble keeping things straight. I like this character. Maybe you could write it from their perspective? I think that could give the narrative a lot of emotional power.” Another technique is going from your personal experience of learning: “I learned that deep diving from one point of view really helped my story to have more empathy and cohesiveness, which made it more readable and powerful.” Look for solutions and improvements, NOT flaws. Improvements eliminate flaws naturally.
This is effective with everyone, not just teens or people who haven’t been knocked off their writing pedestal yet. 99% of beta readers and critique partners (including myself) would do a lot better by heeding this advice. Including with ourselves.