The bed is only a symbol of what is either in your heart and mind (devotion and love) or isn't. Monopolizing the bed is a symptom of a deeper problem. Continuing to give in won't solve it.
Either she believes in your relationship or she doesn't.
Me - male, 42, poly, straight, in a serious relationship with Audrey, also casually dating.
Audrey - female, 20, poly, pansexual, also casually dating.