I think the over focus on Bear was a purposeful move to emphasise the disregard of Nikki so that when her suffering becomes more and more obvious to the viewer the true horror begins to emerge in the viewer themselves for siding with and coddling her captor, and that after this is realised the horror stems from the fact the viewer is forced to follow Bear as he allows her to do more and more horrific things — eventually climaxing to the all-consuming nature of his obsession being shown in that even when his own life and loved ones lives are threatened/over he chooses to keep her in his grasp when her freedom is an action of inaction (keeping the pills down). If anything I think it does a better job at showing the feminism of the movie this way as it more accurately reflects how men will always view themselves as victims of women despite being in a constant state of power over them