I had a similar experience, but on the other side of the situation you describe. My boyfriend got me started on using toys, and for a month or two, we hardly ever had sex without the aid of some vibrating, buzzing apparatus clutched in my hand. I especially loved having vibrations against my clit as we fucked. It usually takes a fair amount of foreplay for me to get worked up to the point where I can accommodate penetration comfortably (he's on the larger side of moderate, and I'm pretty small), so having a toy was like jump starting the engines.
However, one weekend, I forgot to get fresh batteries and all of our old ones were dead. We ended up having a lot of slow, "traditional" sex... and I loved it. There was no machinery buzzing away... there was no hurry. The whole weekend was a long, slow session of just loving each other with nothing in between. I was reminded of how great toy-less sex can be. Now we've sort of reached a balance. Some days we use toys to mix things up, but most days we just have bare-bones fun.
The best way to go about it, if you really are worried, is to talk to her. Be open, be honest... good luck!