Great topic. Here is my input.
I live with my girlfriend. When i first started getting back into bikes (BMX kid growing up) she wasn't really into it. She had a bike but never rode it. I hated her Paul Frank cruiser so in order to get rid of it we had to find her a new bike. I'm a C&V guy so we picked up a 74' Schwinn Breeze for her. I fixed it up nice, adding a couple missing parts and it became a great bike that i was really proud of. Only problem was that it weighed a ton and she didn't really like riding it around town so she never wanted to go anywhere.
So next i bought a 69' Peugeot UO18 with a rare downtube shifter that i dug. This one was in pretty decent condition and after i spent some time cleaning and tuning it up she was pretty happy with it. It's much lighter then her Schwinn Breeze and she's game to go on rides around town with me. She definitely doesn't like to go as much as i do but i'm glad that she'll ride with me when she does.
I had this fantasy that she would go on short tours with me but i've given that dream up and replaced it with the idea that one day she'll go on a winery tour with me, hub&spoke style with hotels.
I wish she was more into it, but i'm glad she's into it at all. She's not loving how many bikes i have around but i can negotiate quite well with her due to her collection of vintage furniture.
My best advice for anyone struggling to get their ladies into riding bikes with them is to find them a bike that is light, runs well and is their definition of cute.