You and a >>>> friend/relative/significant other <<<< are locked in a bare room(cement walls, one window, one door) with nothing left in your arsenal but a handgun with one bullet left.
The glass is beginning to crack from the pressure of the thousands of zombies outside and around your one story safe house. You've been working so hard to survive for the last 6 months but you both are tired, malnourished, and emotionally drained. This is the end, so what do you do with that one bullet? This gun/bullet combo is not strong enough to go through both of your skulls.

Kill yourself?
Kill your friend/relative/significant other?
Kill one more zombie?