I suggest you and your girlfriend do some internet surfing together. Let her show you some sites she likes, the things she finds interesting and maybe that spark will suddenly come up somewhere. If not, at least you will have some fun visiting those sites and looking at some pictures together
It is very enlightening, as you will learn what your girlfriend likes and she can hear your thoughts about it. And of course you don't have to stick with watching and reading, you can try some things out together. The key is to communicate and have fun while doing so