I totally agree with Trailsurfer, except: (lol)
Not only is a 650 taller and heavier, it's more powerful. I had a XR650L, it's not a starter bike, get a smaller one 400 to learn, you're big enough to toss that around a little bit if you need to. I started as a kid too, raced bicycles road racing and moved to power. Actually, mountain bikes are good to get some basics, IMHO.
Then I got off two wheels for a long time and went back to larger cruisers. I have a 1600 now and a Honda Transalp dual sport. I can ride 2 up with either one on the highway or over a field that is fairly firm and flat......grassy areas. IMO, you won't be charging up any rocky hill riding 2 up unless the little lady can ride a bronco. Dirt roads and firetrails maybe as mentioned above, but really, it's not that much fun unless your still in the 20s-lower 30s as I recall.
Get the little lady interested and have her learn to ride her own bike! Get a small one, you learn, then her. She can ride the smaller one and you can step up when you're ready, then sell the small bike and get her a bigger one.
While bigger might be macho, it's not really necessary. My 650 Transalp can stay up with any adventure bike on the long haul, cruise at 75 without pushing it and still room to pass quickly enough! A 650 BMW is an excellant choice, but pricy IMO.
I suggest you study the differences in dirt and adventure bikes and really identify what kind of riding you plan on doing. I had an 750 Virago that I rode off road, it's a street bike small cruiser and your 30" inseam would be overkill as you ride low. Street bikes have gone down dirt and mud roads, over hills and through water crossings before adventure bikes were even thought of as a special group of bikes. And riding two up is alot better. Many modify street bikes, with longer forks and shocks/springs, some dual tires and you're off.
Another dimes worth, hearing what others do, when they strated and how they ride may not apply to you....what you really end up doing will only be found by doing. You need to really identify what you want to do and learn before you get that special bike. Just get a bike, ride it and keep the rubber side down! :bike_rider: