The first information was that your partner did not perform to your expectation. At the same time I read that half year passed your have not been out at the cus

The first information was that your partner did not perform to your expectation. At the same time I read that half year passed your have not been out at the customer front to see if your business model is viable. Just because comparing to a competitor does not mean your business is in the same situation. The low margins, poor brand is both of your responsibility and can have many reasons. As a startup founder you are the face of the company and there is no excuse to not talk to customers and close deals. Your are small team and there is no CEO or VP or Sales. It is you and him to close the deals. If you want your company to survive a simple phrase will do, do whatever it takes. 
And if you think this is not what you signed up for than follow the advice of many, stop it now and fast.