Rose Weasley had never really considered herself to be a rule breaker.
She considered herself to be one of, if not the, most mature of all her cousins, even at the age of eleven. While her other cousins (normally James, Louis and Fred) liked to disobey their parents by practicing quidditch a little too closely to the house, scaring their family through their use of the invisibility cloak, and testing out magical gifts from George despite their mother's orders for them not to, Rose was a rule follower. Rarely stepping out of line, always finishing her homework the same day it was given to her, and always obeying her parents. This was, of course, until she met Scorpius Malfoy.
Before she'd even met him, she was told by her father, "Make sure you beat him in every test" and "Don't get too friendly with him". She had intended to follow both orders, despite her father's somewhat joking manner at the time. But then, Scorpius Malfoy was sorted into Ravenclaw, as was she. Then, he sat next to her in the Great Hall, and she discovered he went for the Chudley Cannons, like her father. Then, she found out he held a liking towards Muggle Studies like her grandad.
And she realised, perhaps her father's rules about Scorpius were not meant to be followed after all.
She still beat him in every test (a fact he hated and repeatedly tried to change), but she certainly didn't distance herself from him. Herself, Scorpius, and her closest cousin Albus had at some point during their years at Hogwarts become the best of friends. They studied, practiced quidditch, attended Hogsmeade, and ate every meal together (despite Albus being sorted into Slytherin). Yes, for the first time in her life, Rose Weasley disobeyed her father - by becoming close to Scorpius Malfoy.
Sure, she felt a little bad about not listening to her father, and she told herself that this was the last time she'd disobey him. But this eventually proved to be false, as well. After telling Rose not to get too close to Scorpius, her father also ensured her that grandad Weasley would never forgive her if she married a Pureblood such as a Malfoy.
Her grandad did forgive her, of course. He quite liked Rose's boyfriend and eventual husband as they bonded over their love for Muggle Studies. Her father eventually came to terms with the relationship, as well, even giving a teary speech at their wedding about his "little girl growing up". Besides, even though Scorpius was a Pureblood and a Malfoy, he was a Chudley Cannons supporter. That was enough for Ron.
That, and he made his daughter happy.