Since connection and relationships are so important to a Pisces, you usually find that you need to set some ground rules pretty early in a relationship.
Do you agree about everything, or not? What is your shared truth as a unit? It's not crucial that you share the same opinions about everything, or even like the same hobbies, music, etc.
But discovering what you do share - morals and other important stuff - helps determine the tone of your "unit" and cements your connection.
This gives Pisces a stronger sense of grounding in a relationship, and helps to preserve its long-term potential.