Try just some day hikes first? But like
>>980113said, make it more involving than just walking around. Try to figure out if she'd be in to visiting waterfalls (my wife loves hiking to waterfalls) during spring runoff, or maybe she's in to birds.
Car camping at the least should be doable for her. What kinna wheels you got? Drive up in the afternoon, have a nice meal, SOME alcohol if she likes to drink some (don't let her get sloshed or she won't remember any of the good parts), and then just stay one night. Try to make it a clear sky day with no weather; I don't have to tell you that starts are fucking incredible with no light polution.
My wife was fine going backpacking with me but I had to meet a few requirements:
1. She had to feel safe and like we were prepared. She likes PLANS.
2. As I found out after accidentally surprising her, floorless tents are an absolute no go. Never ever again.
3. Car camping with our backpacking gear was a great way to ease her in to it.
Let us know how it goes, I'm really curious. We need to refine these strategies and get more girls /out/.