Today I learned that there is a musical version of Pride and Pejudice; in fact, there are several. The one that came to my notice is called Pride & Prejudice: A New Musical, called "A New Musical" to distinguish it from a previous P&P musical. It's rather peculiar; some aspects of the story come through, and there are genuinely funny parts, but some of the songs are absurd to the point of being grating. Part of the problem is that musicals externalize expression of emotion into music in non-subtle ways; this can be done be done well, but it causes problems when the expression is not 'true' to the characters or the story, and the problems are intensified if the original is often quite subtle, as is the case here. For instance, Elizabeth Bennett early on in P&P:ANM sings a song, "Headstrong," in which sings that she is too headstrong for a man to bear. Now, I am very certain that this is not true to Jane Austen's character. Maybe Elizabeth would suggest something as a joke, but it seems very clear that she would be quite offended if someone seriously thought that she was too headstrong for a man to endure. She sees herself as reasonable woman, and this plays an important role in her story-arc; being unmarriageable (which is what it amounts to in context) is not at all part of her self-conception. Indeed, any man who thought she was too headstrong would almost certainly be dismissed by Elizabeth as arrogant at best, and very possibly as stupid. As for Mr Darcy -- I'm not sure I can fully imagine what a musical expression of Mr Darcy should be, but it is certainly not this, and it's a very big problem if your adaptation of Pride and Prejudice cannot make sense of Mr Darcy.
Of course, part of it could be acting or musical direction rather than the material itself; these are also ways in which the music could be true or false as expressive to character. And to be wholly honest, I think even poor adaptations of P&P are worth having, if they ever increase the probability that we will have good ones.
In any case, it's a good example of the fact that emotional expression itself admits of true and false.