Well, as the Girlfriend That Started Playing, I want to point out that this is just as much a stereotype as the gamer stereotype we all hate... I hit 70 before my significant other, I hit 80 before him, I JC to get my own gems, *I* sponsored *his* epic land mount, and I started raiding for that epic gear before him. We raid together now, and we pat each other's back (oh how I love those elixirs of mighty agility he makes!) but if I loan gold from him, I send it back as soon as I can.
She might become the stereotypical girlfriend gamer, or she might start enjoying the game and want to do things her own way. Or, like a couple in our guild, you might enjoy doing things in WOW together so much you just, well, do everything together. Ain't no harm, if you're enjoying it.

My girlfriend loaned me the gold to buy my epic flyer on my second toon in Northrend so I wouldn't have to crawl around at 60% speed while leveling from 77 to 80. Come to think of it she loaned me money to buy the epic flier I have on my main... She also the best healer I've ever seen (I'm not exaggerating). She's carried more raids than I can count.

I've been playing since 2nd Stress Test and got my wife into the game @ a year and a half after release.

It's great that she plays; we chat about the game often and she doesn't feel left out since we are now BOTH on our PC's in the evenings after work. I will say, I have felt a little guilty at times, since there are often more productive ways we could spend our time. But, all in all, I am very happy with the situation.

And...just to help break the stereotype: she spends a much greater portion of her time making money with the Auction House than I do. In fact, she supplied me with the G for my Epic Flying (I love you, honey!).