Do you have sources for that ?
Because in not a lawyer or have any expertise in law but your comment got me curious and what I'm reading seems to contradict your statement.
Like here :https://www.savoir-juridique.com/crime-passionnel-mythe-realite-juridique-droit-penal/
It seems that there is very rare cases when passion was used to lower the sentencing but it's very anectoctical and the "crime passionel" is not recognized by French law


Thanks, I'll have a look at these.
Edit: so, in the case of Marie Trintignant's murder by Bertrand Cantat, the whole trial happened in Lithuania under Lithuanian laws. The crime of passion is a legitimate defense in Lithuania but this has nothing to do with French laws.
For the fact that sexual attacks against women are often downplayed by justice in France, this is a real fact. The recent Pelicot trial really brought this to public light.