Well the sex is without her consense and she doesn't feel pleasure. Maybe is not rape, but is forced (╯°Д °)╯╧╧
The plot is set in an era where these kind of situations were normal. Men would marry whoever they wanted and the woman couldn't say no. If the plot was settled nowadays, she wouldn't have so much disadvantage towards her husband.
And if she was born on the right country that can defend her
You're right, these things happen too nowadays in some countries.
God damn !! This manga is just so realistic and the way the characters are portrayed and the fact that they aren't sugar-coating reality!! Especially, the fact that Madam Giselle ain't a virgin ( I'm not saying I like the fact that she's being raped but most stories involve a 'pure' MC but that's just not true irl there are times when things don't work out and extremely shitty horseheads out there ).