It makes complete sense to me. Smoking is primal. Weed, fire, smoke. It's simple, social, and for most people it's how weed is meant to be consumed.
I've been using vaporizers since 2010, and for years after that I still smoked 1 hitters regularly. It wasn't until the Dynavap came out in 2015 that I was able to stop, since the vapcap was such a perfect analog to a one hitter.
The one form of smoking I've had trouble giving up is the rare spliff. For me it's the tobacco weed combo, and the experience of rolling that I have a hard time dropping. I find blunts disgusting, and I'm too much of a lightweight to smoke a full joint. I also don't care for the flavor of smoked pure weed since switching to vaping. But a little Peter Stokkebye tobacco rolled up with a little bud is great on occasion. The weed makes the tobacco manageable, and the tobacco makes the weed burn well and taste better (I know it's heresy). I know it's unhealthy, so I only smoke a handful a year, but when I do, I enjoy it. I'm not a drinker, and I've always been good at self restraint with my smoking.
This feels like I'm confessing to something dirty, but I don't care. I find so long as I keep it a rare indulgence and not my primary means of consuming cannabis that I feel no compulsion to use tobacco.
But if every time you smoke weed you also use tobacco, as your girlfriend does, you will certainly develop an addiction. If not a physical one, a psychological one, since you will always associate weed and tobacco together.