Questions: Family & Friends

My cousin has dated her boyfriend for nearly 2 years now. However, once in a while the past still hurts her.
When they were 15-16 year-olds, the guy used to be a jerk. He was one of the main social bullies (put bad nicknames on her) and used spread jokes about her facial acne and glasses. While laughing, he once someone would have to be blind or drunk to ever date her. He gave her a hard time and she used to come home stressed out. She hated school.

He came to eating his own words and things happened. I heard karma got him during the summer and he softened up. He worked hard and did so much to be a better person. What impressed her the most was that his apologies and promises were then followed by actions such as when he got involved in anti-bullying campaigns and participated (still does) in a couple animal shelters. He gained her friendship first. It wasn't until late Now 2019 (they were college juniors by then), that they officially started dating.

He's been treating her great since and has changed. He knows she's hurt at times and still apologizes, claiming he'll do anything to make that hurt go away. Needless to say, he informed his friends and I that he was to surprise her on Valentine's Day but not to tell her. He's hoping the answer is a yes. We know what it is. He really loves her. If someone worked hard to amend their awful behaviors and hasn't relapsed since, should they be forgiven?