Sounds like some external influence and/or cognitive dissonance. Don't make it anymore than it is - irrational & illogical anti-gun sentiment and she's in need of some deprograming. Feed her facts. Be patient, understanding & talk to her about it - get her involved in the sport in some way & handle/manage it. Lead her and take her down your own road to where you want to be.
If, on the other hand, her behaviour is intentionally manipulative and/or malicious, you might want to reconsider your future with her.