Naguère is a somewhat archaic and poetic French word that means "formerly" or "in the past." It's not a word you hear every day, making it quite unique and memorable.
In the song, Vianney sings, "Qu'il faut changer, on était si bien naguère" (That we need to change, we were so good formerly). He uses this elegant word to evoke a sense of nostalgia for a happier time in the relationship, adding a touch of classic romance to the lyrics.
Have you ever felt so deeply connected to someone that you just know they're the one? That's exactly what Vianney and Mentissa are singing about in "Parce Que C'est Toi"! It's a beautiful declaration of unwavering love and commitment. They're basically saying, "Hey, if you ever think I'd leave you for something small, or when things get tough, don't worry!" They know the difference between a minor issue and true love, promising, "N'aie pas peur, personne d'autre pourrait / Si facilement te remplacer" [Don't be afraid, no one else could / So easily replace you].
The song really highlights that this person is irreplaceable. The singers express how with this specific person, they're not afraid of getting older anymore: "Avec toi, je n'ai plus peur de vieillir" [With you, I'm no longer afraid of getting old]. It's a love so strong that they'd dare to face anything and forgive anything, just because it's them. They even talk about wanting to have a child, not because it's the right time, but "Parce que c'est toi / J'veux te voir dedans" [Because it's you / I want to see you in it]. It's a sweet, honest look at finding your perfect (even with flaws!) person.