Answer:
The situation is known as "tragedy of the commons".
Explanation:
This occurs when a common resource has no clear defined property rights (does not have an owner) and this leads to the misuse of this resource.
In this case, the common resource is precisely the common space of the room. Because it does not belong to anyone, like the beds, or the personal items, this space is misused by the roommate.
The solution for this problem is to assign ownership of this common space. The space could be divided in two: one for each roomate, and like this, each roomate will have an incentive to keep tidy his part of the space.
