I say just go for it. If your gf really loves you then she'll put up with it. She wont ever have to deal with it if she doesnt want to. If she chooses to warm up to it then thats her choice but i wouldnt really force her to. And if she puts up a big stink about it then maybe shes not right for you. Im not trying to be harsh but its not really a big deal to get a snake. If you get a secure PVC enclosure, some even have locks, then there is zero chance the snake will get out. Which sounds like is her biggest fear.