Its because if she stayed with him she wouldn't be able to follow her dream in france so until he needed to wait until she came back. The guy also was famous already so it was her time to shine.
They can't have long distance relationship? If they really want things to work out, they can.
Maybe they just want to focus on their goals first without things holding them back or the constant worry and other concerns distracting them
It's going to be harder if they're in a ldr because they would always put each other on priority and be afraid to upset each other while the anxiety grew larger, it can hinder their relationship with each other, with other people and their career but with them breaking up they can focus on making themselves and their career grow with the slight assurance that the other is waiting for them.
I Don't understand why they needed to break up with each other?