I'm not going to pay my owings to my classmate
Why are you against paying what you owe?
He has had a massive change of career. He's not in our major any more. I don't know what he wants
You really should pay what you owe to your classmate. His personal life and change of career is none of your business.
Do something about it if you care so much.
I am trying to convince you to do the right thing. Paying back a classmate when you owe money should be a top priority.