Answer:
breadth but little depth
Explanation:
The answer is "breadth but little depth".
Eileen and Roberto are class mates and they study together for their communication class.
They discuss a lot of things in the class together. Though they are close friends they d not disclose or share their personal things to each other. The interaction is very superficial and not deep.
Thus their relationship would be characterized as having "breadth but little depth" as they discuss a wide variety of topics, but they share their personal things very little with each other. They do not talk in depth of their personal lives.
Thus the answer is
"breadth but little depth".
