I think you are right in your analysis of Elizabeth's thoughts on the matter. At the end of chapter 22 we have:
She had always felt that Charlotte's opinion of matrimony was not exactly like her own, but she could not have supposed it possible that, when called into action, she would have sacrificed every better feeling to worldly advantage. Charlotte the wife of Mr. Collins was a most humiliating picture! And to the pang of a friend disgracing herself and sunk in her esteem ...
So this speaks surprise and then hurt over the gulf in their values.
And then Elizabeth adds to all those feelings fears for Charlotte's happiness:
... was added the distressing conviction that it was impossible for that friend to be tolerably happy in the lot she had chosen. (chpt 22). This is of course in the context of a time where divorce was almost impossible.