Dont know much about programming or how hard it would be but how about an option that could enable yandere, kuudere, tsundere or dandere mode depending on certain actions you take with her. Like if you frick more often without the camera or kiss her she starts making comments about that and gets clingy/lovey with you or if you start going to the clothing store or walks without talking to her she starts getting very jealous/suspicious with you? Hell maybe making suggestions of things she wants you to do while you frick depending on which 'mode' shes in, ei asking to hold hands or you finish in her if shes clingy or demanding you do other positions. Just wondering.
Also maybe her riding cowgirl or doing it while shes sitting on the couch or against a wall..