Very difficult situation. If you leave it will for certain take a big strain on your friendship with them. Both of you probably put a lot of capital in that store (either your own or through a loan). If you don’t want your share anymore, are you prepared to pay off the debt on your side? Or do you expect them to “buy” your share of a business which is making nearly no money? Would they theoretically be able to run the business alone? - else their capital and time would also be wasted on that project because you changed your mind. I’m not telling you to stay, but please consider all of these factors. I get that it’s hard. Maybe just take a break. If you have the money hire someone to help your friend out at the bookstore for a few weeks or months. After the break you’ll have a clear mind and are able to make a decision, which you feel is right/fair, not only for you, but for the both of you.