One of the really difficult things about being a writer is getting useful feedback on your work. That’s why finding a good critique group is so important–people you trust whose taste you trust who know something about writing and won’t just pat you on the back or shred everything you do. And even then, you’re going to get feedback that you won’t know what to do with. Things like people trying to rewrite your story for you, or tell it in a different way. And you will doubt yourself when that happens. Because these are your Trusted Friends and they think this is right and what do you do?
What you do is you take a deep breath and you remember that the person who knows the most about your story is you. And you look at what these people are telling you to do and you ask yourself, is this in the best interest of the story I want to tell? Maybe one of your critiquers has a particular hobby-horse about a certain kind of story (“Evil must be punished!” or “The hero can’t get his love at the end!”). Or maybe they’re actually zeroing in on flaws in your story and just telling you about them in a difficult-to-grok way. Take their feedback into account and make the decision that is best for your story.
It’s always a balance between your interest in improving as an author and your confidence in your skill. It’s as bad to take all feedback into account as it is to take no feedback into account. The thing to remember is that all the feedback is valid, and your decision to listen to it or not is equally valid. The feedback is valuable because it’s a person’s response to your story, and if it’s not the response you want, you have to examine why that is. With your critiquers, you have the advantage of knowing them, but that’s also a disadvantage, because it allows you to ignore part of their critiques because “that’s just their thing” or “they just hate this kind of thing.” Maybe that’s true–and one of the benefits of having a long-standing crit group is that they get to know you as well as you know them, so they can just give you feedback like “you’re doing that thing you do again.” But it doesn’t absolve you of the need to consider everything they say.
On the flip side, when you’re critiquing someone, you need to give them your honest reaction to the story. If you know them well, you can add things like “you’re doing that thing you do again.” But try to be honest about what you’re feeling, if you’re bored at some point, if you’re excited, when you can’t put the story down, what sections you skip, etc. And don’t apologize for your critique. “I skipped the part with the department store because I hate shopping” is okay, but “I skipped the part with the department store, but that’s just me so it probably doesn’t mean it’s bad” is not. Your critique is your reaction, and it is as unique as you are, and if you are giving the author the good and the bad honestly and constructively, then you don’t have to apologize.
In any case, you should stay open to further discussion with the author, in case they want clarity around certain comments. But they are trusting you with their work; give them a good, constructive effort. Giving good feedback is a skill that it takes time to learn, and so when you do, make sure you listen to the author’s reaction to your feedback, too. Ask them how you could have been more helpful. Because even your feedback can have feedback.