Ugh

Actually seems natural, imagine you being abuse and raped for years and being condition to believe that this is the only thing you are good for and a man you trust in the past sticks his finger up your butt. Of course your going to assume he wants sex and not wanting to upset a person you care for of course you going to let him have want he wants. It a very sad reaction but has some logic in it. Hopefully the author doesn't use this as a sexy moment and more of a learning moment for the victim.