I can't remember what this movie was called - but I think it was sci-fi or something. There was once scene when some girl kissed another girl in the forest ( and black roses started falling)...

I think you are asking about Electra.
Elektra (2005) - IMDb (http://www.imdb.com/title/tt0357277/)

There is a scene where the villain who drains life kisses Elektra to drain her life. However, it wasn't roses, but dead leaves that fall around them.