Responses
There was a time jump, but the author didn't include everything that happened during those years. We didn't necessarily see the moment He Tian left, we just see when he comes back. I think Jian Yi is in college or went back again to college? I'm not 100% sure about the college part, some of them might've skipped college or went straight to getting a job

The art drastically got better love it but maybe I skipped something?? I don't remember He Tian going away and what happened to their graduation in high school and their college life? Considering Jian Yi is still in school something happened?