Sister's boyfriend wants password to her safe. AITA for refusing?

A safe password is causing drama in the house. A sister's boyfriend, Micah, wants access to her sister's safe and is demanding the password from her. The sister, who was given access to the safe under the condition of not sharing the password, refused to give Micah access when he asked. Micah got upset, reminding her of his status as her sister's boyfriend and that she was just a guest in their house. The argument escalated until Micah left the house in anger, leaving the sister alone and shaken. Now, she's questioning if she should have just given him the password. But was she right in standing her ground? Is it her responsibility to share access to property that isn't hers? Let's find out what the internet has to say in the comments and reactions below.