[ra0x3]

As fzwang mentions, your co-founder relationship IS the business at this point. I'd talk to your co-founder 1:1 and really have some uncomfortable conversations. If you both feel like the relationship is not salvageable, amicably walk away without burning the professional bridge (someone might ask her how you are to work with). If your heart is not 100% in it (for whatever reason) I'd suggest walking away. The opportunity cost of dragging the dead weight of a business that you're not bought into (and that you aren't seeing success with) is simply too high - and can have real life consequences (finances, stresses, etc). There's nothing wrong with walking away - there's a reason the overwhelming majority of startups fail. And most tiny startups fail due to co-founder relationships - doesn't have anything to do with PMF or anything. Think about it over a weekend - have the tough conversation(s) - don't burn the bridge. Live to fight another day. The sun is still shining outside and the NBA is still rigged to always make sure the Lakers are relevant ;)