We both work for FANGA companies in Silicon Valley, and side projects are very common. Both of us are also single (no family), and I'm not aware of personal issues on their side (not that it's not possible, of course).
It sucks because I trust them completely in terms of capability and judgment, so it really hurts that they weren't able to deliver (so far). But you're right that friends don't always work as business partners.
Thank you for the thoughtful advice. Honestly, that is what my gut is telling me as well. Only thing is - I don't have another backup in terms of someone else I could ask to replace them. Do you think I should end this business relationship regardless, or wait until I have found an alternative?
It sucks because I trust them completely in terms of capability and judgment, so it really hurts that they weren't able to deliver (so far). But you're right that friends don't always work as business partners.