Formal:
* Mon bien-aimé(e): This is the most formal and literal translation, suitable for written letters or very formal occasions.
* Mon cher(ère): This is a more affectionate and less formal option, often used in letters or formal speeches.
Informal:
* Mon amour: This is the most common and affectionate way to say "My beloved," often used in romantic contexts.
* Ma chérie/Mon chéri: This is another common and affectionate phrase, often used between lovers.
* Mon cœur: This means "My heart" and is a very romantic and poetic way to say "My beloved."
Literary:
* Mon trésor: This means "My treasure" and is a very poetic way to say "My beloved."
You can also use the possessive pronoun "mon" or "ma" before any word that expresses love or affection, such as "mon ange" (my angel) or "ma joie" (my joy).
Ultimately, the best way to say "My beloved" in French depends on the specific situation and the level of intimacy you want to convey.