Struggling Startup in need of advice

I'm working on a startup with 4 other members. We've been in development for about six months, but now that the summer has started we're all working full time and living together. The change has been stressful-working 12 hours days surrounded by the same group of people is difficult in any sense. Recently things have turned for the worst--we're struggling with our vision, and without a proof of concept arguments have broken out regarding what to do next. The environment is frustrating, discussions are often negative and collaboration is difficult. I find myself unmotivated and irritated on a daily basis. The founder with the most equity is forking up money to pay some of us over the summer (not exactly the idea startup situation to begin with), so it's essentially his project. However, he has been unable to effectively lead the team. Over the last 6 months I've gradually lost faith in him and now feel entirely unconvinced of his ability to make important decisions or accomplish specific tasks. He's failed to produce tangible results and brings next to no skills to the table except significant personal wealth and the initial idea. I constantly feel as though I have to make the tough decisions and lead the group (although I often feel uncomfortable doing so because of his status/equity). We recently switched to a new development framework and are in the midst of a painful pivot. We're probably about a month or so out from launching any sense of product.

I'm passionate about entrepreneurship and love the work I've been doing, but find myself in a bind. As a university student, I can either pick up an unpaid internship gig at another startup (and possibly find a new living situation) or continue working for the rest of the summer under salary. I'd like to salvage the project and the summer, but I'm unsure if things will improve.

Any thoughts and suggestions are appreciated.