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.