Fatigue makes bad ideas sound surprisingly reasonable.

Tiredness changes what sounds sensible. Quitting, sending the message, taking the shortcut, abandoning something you have worked at for years, all can feel obvious and even courageous at eleven at night after a long stretch. The reasoning is intact and the weighting is not.

Make a personal rule that big decisions wait for a rested morning. If it still looks right then, it probably is. Almost nothing is lost by the delay, and quite a lot is regularly saved.