Here is my take on roomates. A couple ruins things.
A B and C live together. A has an idea or something he dislikes. He talks to the others and they take a decision and set ground rules, or argue as a group. This is a healthy dynamic
A and B are a couple. They live with C and D. A has an idea or something he wants. He talks about it to his girlfriend. They now have a couple opinion. They reinforce each other's decisions and wishes. When they present their idea to C and D its not a group decision. Its not a debate. Its a couple that convinced each other they are right, trying to convince two independant entities to see their truth.
When TWO couples share an appartment, then this decision making process becomes a war of opinion. Couple A wants something and they have 50 of voices. They feel by definition they are right. Couple B has the same thought process. Nothing gets done.
There is no assholes here. You just have two couples sharing a space and living their own lives, clashing with each other. Just get your own place.