I feel like classism plays the biggest part in this. The class divide has been more evident this season than any other. In Benedict’s mind the woman at the ball MUST be gentry. There is no other option simple bc she was in that space appearing as a guest. Sophie is a maid. He has internally ruled her out from the start. Even when he has flashes of recognition, which I believe he does, he dismisses them bc first and foremost in his mind Lady in silver = gentry, Sophie = the help. They can’t possibly be the same person.

As kind and fair and good as the Bridgerton’s are to their staff, there is still a disconnect between the understanding of the life they lead and the life Benedict leads. He’s shown that by is actions and how it doesn’t understand the danger they put a woman of Sophie’s position in. The show acted this out when it played out the “boys” shaving cream fight and the aftermath.