You are correct on the NRE issue. And this is always the hardest phase for everyone involved. Calling it what it is and talking about how traumatic it is, is the only medicine.
Let your GF know that you understand, but are human and have feelings too. Ask for a little consideration is this too please. How she reacts will tell you a lot about the real depth of your relationship.
The NRE passes in time for everyone but it's never a painless process. Try to be patient and understanding, but keep communicating about your needs and your own relationship.