The asexual story: the sister is just completely dismissive About how sex makes op feel. Plus, like op Said, if a couples can't go a full day without sex, it's honestly pathetic.
The asexual story: your aversion to normal life actions is your problem, not anyone else's. Having sex on someone else's bed is nasty, I agree with that But I get the impression that op was a sexialityzilla from the start.