When I first read P&P as a teenager I was very caught up in the hatred to love romance of Lizzie and Darcy. I'm still a sucker for that sort of story arc. For a long time I thought Charlotte was cheated of a happy ending, I thought she deserved much better than Mr Collins. I still think that she deserved better but now that I'm much older I can see that it isn't an unhappy ending either.
I still wouldn't want Mr Collins for myself but I've been listening to Dr Octavia Cox on YouTube (she's great) on various aspects of Jane Austen's books and when she was talking about the nature of marriage and Austen's examples of good and bad marriages it helped to make it clear that, actually, Charlotte could have had a very much worse story arc.
Mr Collins, for all that he's annoying, isn't a bad husband. He clearly respects and listens to Charlotte, he allows her to direct him in a way that makes the marriage comfortable. For instance, she encourages him to work in the garden for his health, and he does. She has a lot of freedom to run the household to suit herself. I can't think of anywhere in the book that Mr Collins is rude or unappreciative of Charlotte, certainly not in the way the Mr Bennett often talks down to or is dismissive of Mrs Bennett. Mr Collins clearly feels that he chose his wife well, he likes his wife's family and gets along well with his father-in-law. She fits the advice of Lady Catherine, useful sort of woman and genteel enough to be in high-level company.
While she misses out on true love, there are lots of ways it could have been so much worse for Charlotte who didn't have good looks or a large dowry. She also seemed to have passive parents, for all that Mrs Bennett is a bit crude and pushy she is at least striving to get her daughters well-settled, Charlotte's parents don't seem all that bothered about her future. It would have been uncomfortable to be a spinster and reliant on her brothers for her whole life. She also might have ended up with a husband with a vice, eg abusive, a womaniser, a gambler, an alcoholic.