I think that "one more final farewell to their respective lovers in private" has a better chance to be the right situation. One more thing: "adieu les filles de mon pays" may mean "farewell you girls from my country" but it might also mean "my area". The same notion of "pays" meaning "area/region" could also be found in "mon pays/ma payse" which meant "someone from my village/town/area" (we don't use these words nowadays except for Brassens in "Le petit joueur de flûteau" but he would use some old words).
About how old it is, I've emailed an association that collects trad songs in Morvan. I'll post their answer as soon as I get it if any.