You both look pretty solid. Your girlfriend was a little mechanical, but maybe that was caused by the video.
She could work at getting more relaxed top to bottom. Next, have her work on her body angle and spine tilt. Both will help her open up as the ball goes back and be in a much more athletic position coming forward. By open up, at the apex of her back-swing, her body should be opened almost 90 to the lane. Again, look at your video for an example.
Have her stop-frame through your video to see what I mean, then compare to her own. She should get a lot more on the ball if she does. She could also drop her right shoulder a little and work on the position of her balance arm throughout. Maybe start with it forward and then thumb-down palm-out as the ball comes forward and her balance arm goes backward.http://bowlingknowledge.info/images/stories/slowinskioct10_swing_slot.pdf
Finally, you both could work a little on your foot-work cadence. Slow, slow, quick, quicker, quicker to put you in the best leverage position to snap the ball off your hand at release.
I only bring this up, because bowling is about speed and rev's coming off the lane pattern. That speed and those rev's will come from good technique, not physical strength.
For your girlfriend, have her watch videos of New Hue Fen and Daria Pajak for motivation. For you, E.J. Tackett and Tommy Jones.