The first half of the dream is a strong release of your pressure and emotional depression in the dream, and that man is the image of the problem you are facing. You are chased by him, but you will eventually solve him. You become a female classmate because you feel guilty about such a dream (or the way to solve the problem), so the subconscious will borrow an irrelevant person to comfort you a little, which is unnecessary.
The second half of the dream is actually the result of your mental fatigue, and your brain comforts itself as an adjustment. Walking all the time also means that you are very tired, which means that you have to rest and adjust properly.
Dreams are not a sign, but a reflection of the present mood. I wish things well first, and I hope you are healthy.