For me, a major "transaction cost" is just picking that flexible date. And after a few failed attempts, which is totally understandable (kids, jobs, eldercare, etc), friendship equity suffers.

I've tried a handful "let's make a date" apps. None really work. Worse, I can't figure out how I'd do better.

One crucial missing feature is shared calendar event updates. For example, you need to push back our lunch 30 minutes, my calendar gets auto updated.

That would be divine!