Translation - French-Spanish - 'Je serai ta maîtresse'

Hi Italo!

I don't know if "favorita" is the best choise here.
maîtresse. But maybe I'm wrong.

Madeleine

Hello madeleine78, "favorita" isn't wrong. It's a synonym

from wikipedia:

A mistress is a man's long term female sexual partner and companion who is not married to him, especially used when the man is married to another woman. The relationship is generally stable and at least semi-permanent; however, the couple do not live together openly. Also, the relationship is usually but not always secret, and there is the implication that a mistress may be "kept", i.e. that the man is paying for some of the woman's living expenses, or provides her with an allowance.

The term can also be used to describe the "other" companion in a female same-sex marriage. Likewise, a woman may be married to a man and have a mistress of her own.

Unlike a concubine, a mistress has no legal relationship to the man.
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Der Begriff wurde umgangssprachlich auch als Synonym für „Geliebte“ benutzt, ist in dieser Bedeutung heute aber veraltet. Ein inzwischen ebenfalls historisch gewordenes Synonym ist Favoritin, doch bezeichnet dieser Begriff wohl einen weniger offiziellen Status als den der Mätresse.

Hi Italo, I didn't say it's wrong. Just that I wasn't sure it is the best choice.
Thanks for replying.