
I have a terrible and tragic theory. If we assume ML was the female friend having disguised himself and staying with her family for his safety we can then assume the need to do so was because someone or some group was after his life. And in her flashback just now when she recalls her parents murder is about the age she had the female childhood friend with her. I am then thinking her parents are killed for harboring or have harbored the ML. So indirectly ML caused all her suffering so even if he loves her he also feels he needs to take responsibility for what has happened.
Further I think what happened after their death is ML had Neighbor’s take her in and the reason they kept getting richer is ML kept sending them money to care for her, but they abandoned her instead, but kept telling him things were going great and she was happy. The ML then believes she is safe and puts off going back for her as his life is still in danger and he doesn’t want her getting killed like her parents. It’s only once he discovers what has actually happened that he goes off immediately to get her. This would also explain why nobody in the mansion is surprised by him suddenly bringing a commoner home as his wife because they are trusted allies and are aware of the danger to his life and her parents killing. The fact that they know she suffered so much protecting their master also shows why everyone is extra kind to her

FL telling her brothers about what happened : So from henceforth I will refer to the young miss as the nutcracker
Young Miss who was let in without FL’s knowledge having been standing behind the whole time, but is strangely Excitedly: Is Because I’m beautiful and elegant like the ballerina in the play?
FL looking away with eyes wide opened and a strained barely concealed panic: Errr… yeah let’s go with that
Young Miss getting even more excited: Thank you so much I’m going to brag to all my friends and family that I’m the Nutcracker!
FL panicking a little and trying to think of something on the fly: NO! No! Don’t do that!
Young Miss shocked and visibly becoming visibly crestfallen:…oh… okay…
FL: No no. Don’t cry it’s just that nicknames between best friends so be kept between us. It’s kind of like a secret we share
Young Miss perking right back up and absolutely beaming with happiness: I didn’t know we were best friends.I’m so sorry of course it will be our secret
FL letting out a sigh of relief: I’m so glad you understand
Young Miss: But then you need a nickname too. I know! Going with the Nutcracker theme I’ll call you the Buttcracker because you kick ass
FL holding a strained smile in place while trying and failing to sound exited:….yayyyyyy
Young Miss: Oh I’m so glad you like it Buttcracker
FL:….

I’m just sitting back reading about Blanche going to her father while doing the finger steeple of evil and going “Excellent. Excellent. I see you started with a show of cuteness and appear to have brought some snacks to make him lower his guard. Now when he lowers his guard finish him with tactlessly honest little kid statements and questions

Polar Bears hiring practices
Polar Bear: Oh hey, somebody survived my murder rampage. That must mean they’re pretty skilled. I should hire them as my bodyguards
Assistant: Well that seems like a terrible idea. What if one of them wants to take revenge for all their friends you slaughtered?
*BANG* Assistant drops dead for gunshot wound to the head
Assistant Two: … well I think it’s an excellent idea
Sometime Later During Job Interview
Interviewee: I mean he killed all my friends aren’t you worried I kill him?
Assistant Two muttering to himself: Better him then me
Interviewee: What’d you say?
Assistant Two: I said we know your a professional who keeps his emotions out of the job
Interviewee: Well alright then can’t see how I could say no when your paying 10 times my current salary
Assistant Two: Excellent now let’s let’s go over body disposal and how to bill us for dry cleaning when you get covered in blood
Interviewee: Wait what?! How often do people die here?
Assistant Two: let me put it this way. I’m his 34th assistant
Are you quitting while your ahead?
Why yes, yes I am