Plain old stink. It’s painful.
Those who can find the good in the suck are plentiful, and I admire that. And, sometimes there isn’t any silver lining.
And that’s ok, too.
Being able to both feel the pain and get past it (not get over it, just past) is not always easy but, as always, time doesn’t care about your pain.
Keep working. Have a system that doesn’t get derailed by failure. Otherwise you don’t really have a system.