By a bad manager maybe, a good manager would figure that you're going to be unreliable moving forward and slowly manage you out of their team / key milestones until you eventually quit.

No it isn't. And if it is, that's a place you don't want to work and do want to see go out of business.

Maybe that's a blessing in disguise.

Problem solved?

Oh my, we posted the same thing at the same time ;)

which may be the best thing. Burn the thing that is devastating you.

As a general rule of thumb, this is nonsense. I've spoken with many managers about feeling demotivated, and I have yet to be fired.