I searched on Google and it looks like maybe it could be this film?
La vie d’artiste
FRENCH FILM by Marc Fitoussi, 2007
COMEDY – 1H47 – all audiences
WITH Sandrine Kiberlain, Emilie Dequenne, Denis Podalydès…
Alice is an actress, Bertrand a writer and Cora a singer. Well, yes and no. Alice dubs Japanese cartoons, Bertrand teaches high school French and Cora emcees at a karaoke bar. All of them dream about fame and success. But the road to glory is often paved with bad intentions. This movie is a serious yet light-hearted portrait.
Vie d'artiste, La (2007) - IMDB
If that isn't it, maybe someone else has an idea. Good luck!