Meatloaf was 66% correct

Some of the rudest actions I have ever been witness to is a non-technical co-founder asking me for a status update on a difficult problem.

Pulling me out of flow.

And within a minute of me starting my explanation the co-founder is staring at their phone; checking their email, checking messages, or whatever.

At that point in the early days of a co-founder relationship the three foundational aspects of a good co-founder relationship (like, respect, trust) become one (trust) and it will take a lot of effort to gain back the missing two.