Sirens - Giddy is drunk.

At some point, something is troubling young Giddy, and her friends tend to make sport of her and aren't much help. She spends a lot of the third act drunk on absinth and/or professing to be making some grand change in her perception or her function in life.
If this has made you curious about this movie, you can read a review at https://www.vaguelycreative.com/tvandflim/Sirens