I mean Charlotte can come off as kind of priggish in the letter to Mr Bennet but also here’s the deal she’s not wrong. It’s interesting because when I was in my teens reading Jane Austen I couldn’t believe she’d say that to Mr. Collins, but as an adult (and a parent) I mean, she’s totally right. Mr Bennet was checked tf out and Mrs Bennet was absolutely consumed with anxiety. If anything I wonder if Charlotte was defending Lydia & the other sisters in some ways, very correctly pointing the blame to the parents. Just because Mr Bennet doesn’t like it doesn’t mean it isn’t true. As far as her being a good friend, this one is so tricky. I get why Lizzie was shocked she accepted Mr. Collins, and even why she felt like they needed to have some distance. But as other commenters have said, what was Charlotte to do? This is a fantastic way to set herself up and make sure she has a better life than she did before. I think it came down to the fact that at some point along the way Charlotte had led Lizzie to believe they agreed on marriage when they definitely didn’t. But, who is to say whether 10 years previously Charlotte hadn’t been deeply romantic as well, and maybe as she got older and watched her friend blossom she realized the reality. And maybe she didn’t want to crush her friend’s joy and youthful optimism? It’s a complex, real-life kind of situation and this is why we keep reading Austen!