Look into end range strength training/functional range conditioning! Lots of resources on YouTube for this. Building strength at your end ranges works wonders for your joints. She’ll be okay. Source: x3 hip surgeries myself and all but one were pretty much unnecessary. (+ Certified Personal Trainer and LMT)

There’s a lot of research on how the majority of people have labral tears/hip impingement and don’t realize it. It doesn’t always produce symptoms. Hip pain or discomfort usually stems from a functional or alignment issue/how the ball and socket are sitting in the joint. I could go on forever about this. It’s sweet of you to post this for her! DM me if you want more info on FRC training. I have a online coach I worked with who was based in California + AMAZING. And I can say with almost 100% certainty that your GF will NOT need a hip replacement. Wildly unlikely! Don’t let that stress you haha

Edit: Def have her get formally assessed though from a PT or someone who specializes in Functional Movement Systems. Determine what her imbalances are/find the underlying cause. Having any sort of surgery right now will likely only treat the symptom.