I think you may have just grown differently, he might very well think you're not focusing on the right things either at this point. Assuming you're both reasonable people and you want to fix things with him. You could try this;

Get away from the office and have an uninterpreted "strategy session". Sometimes leaving town and relaxing a bit helps. Do something fun, not business related for a night then the next day have a conversation. Start with facts he can't dispute that are not personal. Something you can both agree on. Like, can we both agree that the business is sinking and only has X months left? If you can agree on that, the next question is what do we need to change to fix it? You can bring up some of the issues without personally attacking his style. A la "I think we need to listen closer to customer feedback and focus on revenue generating opportunities within their feedback"

I've worked with a lot of personalities that sound familiar to your co-founder, the trick is planting the seeds so they think it was their idea/or they were at least apart of the ideation process - when really it's exactly what you wanted them to do and your purpose for engaging in the conversation. Not everyone can just be directly reasoned with or is receptive to direct feedback.