All I can say is be grateful for what you have.
My girlfriend recently cut her waist-length hair to shoulder-length because she couldn't take care of it. It was tough at first, but once i realized I could still climax from her hair, I stopped caring about the length.
It's hard enough to find a compatible romantic partner, let alone one willing to maintain waist length or longer hair who can also indulge this very specific fetish.
If your girlfriend cut her hair one day would that be enough for you to move on? If so, you do you. But if not, then count your blessings, lower your consumption of long hair content, and focus on loving her as a person first.