I'm going to flip out at my partner for leaving the door to my room unlocked
Why do you want your door locked?
Because it's my room!
If you're in a healthy relationship then you won't flip out on your partner for simply forgetting to lock a door, especially a room door which typically don't get locked in the first place. Talk with them about it in a calm manner and explain that you like your door locked and you will see much better results.
I guess you have a point
I don't want to know the details of your relationship but the outcome and ways to keep a relationship should be the same for everyone else. Be nice to each other.