Thanks for the chapter!
Think the problem with her family was more due to bad communications and not knowing how to interact with their genius daughter rather than favoritism and intentional ostracizing. Mother had mentioned MC was basically one handling all the house's accounts and was going to be a mess before MC left the house to travel. It's also hard for a parent to teach a child who's smarter and more talented than them not to mention awkward. Her sister on the other hand was open, bright, outgoing, a complete idiot who rode emotional highs and refused to think or use her brain. Then there's the mixed messages and misunderstandings such as the MC telling her family they don't need to trouble themselves by coming to the wedding when she does want them to come.