Girl Bike?
Dude...that's clever. However, if you are just looking to get out of the relationship, how about a nice dinner in a public place, or fake your own death instead of leading her to hers. I can hear it now, "sure baby...just give the throttle a quick twist...you'll be fine."
Seriously though, I've known of two different women who have ridden the litre sportbikes...one on a Blackbird and one on a 2000 ZX11. They both complained about the weight. One ended up on a 750 Shadow Sabre and loved it, and the other a CBR F4i and loved it.
Good luck!