"Second guesses" refers to doubts or uncertainties that arise after making a decision or forming an opinion. It means questioning or reconsidering a previous choice, often due to a lack of confidence or fear of making a mistake. Full definition
The quality is impressive and something you shouldn't second guess if you were wondering of just how well they would look in real - life. (playstationenthusiast.com)
You may start second guessing what you should be saying. (elitesingles.co.uk)
I'm not someone second guessing everything he has done. (sbnation.com)