The sixth ending of Twelve Minutes is called Continue. This page explains how to get it. This ending allows you to get the Uroboros achievement.
This ending can be reached after the Alone ending. You will go back to an empty apartment and pick up the watch from the bathroom again. The clock is not working this time - you have to manually point the clock hand to two to twelve. Now, however, choose exactly the opposite answers than in the Alone ending i.e.:
- You want to be with your wife,
- She doesn't need to know anything.
After that, you will return to the apartment, where you will meet your wife again.