Can we be game master as a couple?

My girlfriend and I enjoy developing my D&D world a lot. We spend much time talking about what the backgrounds of characters are, how history has developed, what the relations between the different kingdoms and peoples are, what the hidden agendas of the villains are. Her ideas have enriched and improved my world a lot.

At the same time, I’m running a campaign in this world for a couple of friends that she isn’t part of (for logistic reasons, long distance relationship). But eventually, we’ll move together, and I don’t want to miss out on GMing, neither do I want to miss out on developing the world together, and it would be great to finally be able to play together. This leads me to my question:

Can we both be GMs together? How do we split the tasks a GM faces in a session? We’re fine with developing the world and the campaign together, but how would we play out an NPC’s dialogue with a player? How to agree on DCs and skill checks? And so on, and so on.

Could we take turns? (E.g. every session, or every hour?) But won’t one of us be bored, having nothing to do? We can’t really take up another player, because we know all the GM secrets, making it hard not to meta-game. Or could we divide up rooms, regions and NPCs amongst the two of us?