I am a student and have worked in a 3-person team on a project for some time now. In this team, I have all IT roles (but mostly programming), and am currently having a conflict with a person who has all of the business+management roles. This project used to take me around 2 hours a week, however we have just started the main phase of the project, and that is making and programming the prototype. On the last meeting we had, we discussed what we had done so far and the person in conflict with me thought I hadn't done enough. I had spent about 4 hours on the project in the 2 weeks prior, which he judged as not being enough. I asked him what he sees as enough, and he said that he would appreciate about 2-3 hours per day. Unfortunately, this came at a time of much work to do, and right before a holiday. I only have about 3-5 hours of free time a day and a reduction of 2 hours would be very noticeable.
All three of us are underage (though over 15) and the reward would be a stake (1/3) in a newly created company. We would likely not receive a salary. The company also likely won't be profitable until around 2 years later.
I would like not to have to quit this team, as I will be studying with this person for years. I have talked to him, and he just says that he doesn't have much free time either. What are my options? I do not have other job offers at my age.