Is not like our MC never lived in luxury... why would she be happy with luxury life if she never been happy in her own household, where she could get anything money can buy. The duke is stupid. I know the duke is richer than our MC family but is not like she live in poverty either to be happy just because luxury goods. And why would he proposed an engagement thing to our MC if he didn't even try to welcome her and just be busy with serenia girl. That duke doesn't even try to make her happy. He is full of bullshit when talking to other people about making her happy.