Air carrier First Officer reported during climbout the fuel quantity system began to show an increasing imbalance between tanks. The pilot returned to the departure station.

Narrative

On climbout captain noticed a 200 pound imbalance and stated when we get to cruise we need to balance fuel. A few minutes later I looked down and noticed we were losing fuel rapidly out of the right tank. The imbalance was now 2000 pounds and increasing. I pointed it out to the captain who was Pilot Monitoring (PM). He [requested priority]; notified dispatch via code on ACARS and started to run checklists. While he did that I turned us back to ZZZ and setup for the approach. During this we had the Flight Attendants (FAs) look out the right wing to see if they saw us loosing fuel. The Captain (CA) also briefed them on the return and that it would be a precautionary landing. The checklist had us shutdown the number 2 engine. The Captain shutdown the engine and I continued us toward ZZZ for an approach to Runway XXR. We had an uneventful single engine approach and landing. Clearing the runway emergency vehicles looked and didn't see any fuel leaking. We returned to the gate and gave the aircraft to Maintenance.