The parties used to work together, it was unthinkable to not compromise for their constituents. Today we hear politicians talk as if it would be treason to work with members from the other side.
There is no both sides in this either. One side wants to govern alone to their own interests, not those of their constituents.
Or as one party drifted left, the other overcorrected to the right.
I still think Reagan had a big influence dividing the house.