Same with grandma, after the 5th time I just roll my eyes whenever she appears because you know its going to be some blueball bullshit, probably getting naked and laying on bed with MC scene for the 10th time. I actually tried to have a playthrough where I rejected her everytime to avoid the constant blue balling but it changes nothing.
And at this point I lost interest in her, where it happens it would probably be some boring vanilla shit anyway, when MC is already pissing on bitches and gaping assholes, no need for some old hag playing hard to get.