The dhamma can be for everyone, with or without a relationship. There are a lot of people with relationships who have made it work. Some may even be able to do it better with a relationship than without. I had a relationship when I started with meditation and having the precepts as a guide, while she didn't. It worked and we split because of other reasons.
I don't really see how you keeping the five precepts can be a hindrance to her? Isn't it only positive for her that you restrain from lying?
One thing is for sure, you can't force them -or any other practices- on her. If you want to follow the path, you can and should, it's marvellous. But if she doesn't want to do that, she's free to of course.