I feel like everyone forgets how much Remus hated himself. He probably couldnt look at himself in mirrors and being as lonely as he was didn’t help with the prison he was in in his mind.
There are so many reasons for Remus to be the way he is, staying away from Harry, not introducing himself the way he should have, not telling Harry he knew his father until he had to and all the things some of you are angry at him about. He hated himself so much and he thought he was guilty for sure about the things that happened. He probably didn’t think he deserved Harry in his life and that’s why he was so distant