The Alone ending, is one of seven possible game endings in Twelve Minutes. This page explains how to get it.
After unlocking all available information and knowing that you are the murderer of the wife's father (collecting all information from the wife, interrogating the police officer three times with evidence and getting his confession earlier), the pocket watch you got from the bathroom will start to move backwards. Wait for the hands to move to 2 minutes before a full hour, and in the cutscene select the second dialogue option related to no life together with the wife. This leads to two more endings, 6 and 7. After that you will see the end credits - but you'll still have access to further endings.