I had a girlfriend last here. She was 10 years younger than me and was studying music, so she did not understand anything about math, or programming, or markets, or startups. And she needed not to. I was happy with her, she gave me the support I needed in doing my work even we did not speak about anything technical.
If I was feeling bad about something in my work, I spoke with her about what worried me and my feelings, not the technical problems I had. Girls, and especially your girlfriend, are not interested in how things work, but in how you feel. They are not interested in solving problems, but in supporting you.
Leave to your girlfriend what they are their "duties", give her the place she deserves in your life and not in your job. For tech understanding you have your cofounder, friends, fellow entrepreneurs and HN.