It's a REALLY glamorous poolside outfit, I'll give her that.
And appropriately dramatic if you want to sweep out of somewhere in a huff IN A BATHROBE, like if your boyfriend uses the rest of the marmalade and doesn't replace it and you have a big fight at the breakfast room table and then you need to make an exit.
Even her makeup is bored.
I guess a tee shirt is more committed than a robe? I mean, you have to stick your head through it and all.