Hi MilesFish,
Welcome!
First, I am sorry for your pain

.
Remember, God has plans for your welfare, not woe. He will not throw anything at you that you cannot take. Just be open to His will (even if it means a break-up or move).
For the time being, it doesn’t sound like anything is set in stone, so unless/until plans (not just talking or considerations) to move back to France are being made, I would not worry too much about it, since, as you said, there is not much you can do anyway (and our Lord wants you to be happy if you can). Also, wanting to go back is very different from planning to. Sure they love the place, but moving requires finding a new job, finding housing, and if your going to a different country, there are even more things to think about (passports, will education transfer…etc.). It still seems a long way off.
But if she should happen to move…
It sounds like you might be a student, am I right? Adults and college-aged students frequently have to deal with long distance relationships. They can work, and if you think she’s God’s plan for you, you can try it, though I would not normally recommend a long distance relationship unless you have some foreseeable end to the long-distance part. If you are as young as I guessed, you may be a little young to be commited to someone you won’t get to see in person for an unspecified length of time. If you knew she was coming back, or you could move there in a few years…that’d be different. Sorry if I sound a little blunt, but I really feel as though you need to hear this.
I hope all works out.
A prayer will be said for you tonight,
CotL