The lady here is none other than
Spoiler!
The Duchess and she uses magic to hide her hair color which is pink in color.
Ms. Grave keeper getting jealous
Spoiler!
of her husband
because Ruby really likes him but can't express her feelings 
and a spoiler when it's revealed she is a mage and thr reaction of her family 
Spoiler!
It was during a trial academy event. On the last day, 'Second' infiltrated the academy in hopes to find 'Seventh'/Ruby. So Demon King Magician linked himself through Second's mark so a demon was also summoned and caused destruction in a part of the academy. So Ruby had to cast magic to protect herself. She was almost in grave danger but thankfully Dad and mom arrived just in time and protected her. Even while in danger, Ruby was worried about her parent's reaction. So that how they learnt she's a mage. And they finally realized why she did all that because she had to really hide her gender and why she's like on the run/hiding and why she have nightmares. It was because she was the mage that was sent on the battlefield at a very young age and that's on the run and being pursued by the Demon King. So the parents were mad because she's just a kid and she endured a lot.
There's also a moment during the chaos where Ruby was trying to explain first why she hid the fact that she's a mage and that she already deflected and she's not an enemy because she was scared she'd be abandoned but Dad reassured her and then she cried and just asked for help. She finally asked for protection.
I like to post spoilers for the stories I find interesting because I don't have much time to read novel due to busy schedule
you will find me in most romantic historical manhwa comment sections 
you will find me in most romantic historical manhwa comment sections 
