Actually, you are holding on not because of who he is right! But it sounds like because of who you believe he could become. Eight years is not a time to judge your relationship based on time, it’s just a pattern. You may noticed that he is avoiding the conversation together. When someone avoids you to talk about future, it’s means you are losing your relationship slowly.
You are moving and you are about to become a doctor. But, his life seems paused. I know love matters but in a long term, everything is matter like direction , support, respect and stability. You don’t want to lose him but how can you stay with him as he is today. Because building a future based on potential often leads to displeasure later.