Have you told her about your goal? Maybe if she understands your goal she'll make her own or at least get why you might go off the front sometimes. I too have a couple of friends I ride with who are not as fast as I am. I actually see those rides as "social" rides and make sure I go out for more "training rides" where I push myself or go out with my SO who is much faster than I am. Maybe you could connect with some other riders who are more your speed or faster. Just some thoughts. Good luck.