
I think it would be interesting and sensible for her to live without marriage. Her own nanny, Mary, isn't even married and still raised her. Why can't she do the same? Also, where the hell is the prince? He needs to collect his wife.

I think the King and Queen wish for her to a wet nurse/nanny for their future child(ren). You kinda need to have just given birth to fulfill that position and it would look poorly for all parties if she got pregnant out of wedlock. The King and head guard were milk brothers (ie nursed by the same person). Mary and ML seems somewhat close in age so probably appointed during childhood, same as ML with the Queen who was 9(?). Obviously at that age you don’t need a wet nurse.
Why is she so mad about her mother-in-law just living life... even if you dislike her just ignore her? They live in different buildings and wilmena doesn't even go out of her way to socialize so there should be no problems