Traduko - Franca-Japana - Mon amour me manque

littéralement : "nostalgie(s) de mon amour"

Romanized:
Sugita ai no natsukashisa
Literally:
Nostalgia for a love that has passed

The Japanese already implies (although it doesn't actually _guarantee_) that it's "my" love that has passed, so I couldn't get the "my" in here without making it sound unnatural...ó_ò

If it's about the _man_ she loved (i.e. the "my love" is an allusion to him), then it would be
愛していた彼は懐かしい
Romanized:
Ai shite ita kare wa natsukashii
Literally:
I'm nostalgic for the man I loved

(I translated it from the remarks indicating the literal meaning, under the French translation.)