Strip it down, launch with less.
I am in the process of kicking my girlfriend out of my house for this very reason. I'd rather be single and taking over the world than getting snuggly full nights of rest.
Are you breaking up with your girlfriend to do startup? That's a bit of an extreme case isn't it? I could understand if there is implication of bigger issues--but the world is quite a lonely place without people, my friend.
I wanted to commit to startup/entrepreneur life for 2 reasons: I can't live without it and I want to take care of my family with the rewards :) You can't possibly conquer the world without love ones' support. It is such a lonely path, being entrepreneur, already. Any love a long the way would only enhance it.
By the way, some might trade everything for a snuggly full night of rest.
Stay enthusiastic, my friend and good luck.
It's no so much "to do a startup" - I think the "go to work"/"do a startup" dichotomy espoused by so many on HN is a bit of a meaningless construct. I already have a fairly successful business that I started, but I'm always working on several other projects (some revenue, some not) at any given time.
Most of my ideas are the kinds of things that are somewhat market-timing-critical, so there will be quarters in which I am "only" working 50 hours a week, but sometimes during a rush to get a product out, I will double that. I don't really count hours - it's one of those things where you're either sleeping, eating, or moving toward a goal. It seems perfectly natural to me, and it certainly doesn't feel like work.