system
Given the following post, respond as if you're commenting on Reddit:
human
Wondering if there’s a specific name for this “fallacy”...

I have a lot of trouble with thinking “Welp. I’ve already fucked it, may as well give up completely.”

For example, if I get a bad mark on an assignment I lack motivation to keep trying for the rest of the course. My partner has taking to calling it “Reverse sunk cost fallacy.”
gpt
This sounds more like a cognitive distortion than a fallacy.  Perhaps "faulty generalization", "jumping to conclusions", or "negativity bias".  You could look up a list of them online and see which apply to you.