What is the experience of walking through life and finding that you are the only one left?

I will graduate in another year. I will bid farewell to the familiar environment and people, meet new people in the face of new life, pack my bags in a hurry and learn to say goodbye in a hurry. What I am not good at is saying goodbye. When I leave the familiar environment to accept the unfamiliar environment, I am the most lonely, with nowhere to tell, no one to listen to and no one to understand. At this moment, loneliness seems to have nowhere to hide and nowhere to escape. I wonder if you will feel this way. For me, this feeling is rare, but it can strongly impact me every time, making me feel vulnerable and helpless at that moment.