While it's mixed in amongst a bunch of other detail, several related reasons are given: "…an irreconcilable working relationship rooted in fundamental differen

While it's mixed in amongst a bunch of other detail, several related reasons are given: "…an irreconcilable working relationship rooted in fundamental differences in personalities and misaligned expectations of roles and responsibilities…" "…the startup would never be something I could call my own, not just in stake but in equal say… …in this case the lack [of a sense of ownership] tore [the startup] apart…" "…it just wasn’t fun anymore…" More specifics about the irreconcilable clashes over roles and sense of ownership would have been great, but there's enough to see that there were unpleasant disagreements between friends that got worse rather than better over time, and it made more sense for the author to leave than others. Happens all the time among people with strong opinions and unclear areas-of-mutual-deference...