<p>What mistake did the roommate make? Did the roommate leave the door unlocked? NO!!! The roommate bears no responsibility for the OP’s poor decision. The OP DID NOT have to leave the door unlocked, they CHOSE to leave it unlocked. How can you possibly think the roommate (moronic as their attitude may be) be responsible? Did they somehow force the OP to leave the door unlocked? Get serious.</p>