@Hollow7F The older brother told the little bro everything about her (according to the little bro anyway) it wouldn't surprise me if little bro was told about her school or workplace at the very least.
I'm going to assume that she wasn't with the older brother very long if she never met his family yet.
Another thing if his older brother was two timing her from the beginning the little brother should have said something to her from the beginning.
If you think a doctor can't be at the front lines then you haven't read "This is the Wrong Way to Use Healing Class" yet (Pardon me if I got the title wrong)