This is one of "22 virus definitions" (thought-mistakes that cause ineffectiveness and unnecessary negative emotions).
For example, let’s say my wife says something kind of hostile to me, and I get upset by that, focusing on the fact that she is hostile and ignoring the fact that we’ve spent the last two hours in a great conversation, and also ignoring the fact that immediately prior to her being hostile, I said something insulting!
When you’re looking at your negative statement (using the basic technique), look for this kind of tunnel vision, because it is a mistake. You’re leaving out other facts that would make your explanation of the situation a lot less upsetting. It's a mistake by omission. What you see may not be a mistake, but you're leaving out other facts that would ease your suffering or eliminate your feeling of discouragement.
See the complete list of definitions: The 22 Virus Definitions.