I don't think that's what barcelona was asking, was it? I think you're asking (but I might be wrong!) if a couple will have to be working to get benefits.
The answer to that question (but perhaps not the question you were asking
) is 'no'.
Universal Credit will be payable to all working age claimants. However, the ceiling for UC 'conditionality' is possibly going to be 35 hours at NMW for both earners if you have no children. If you have children, the age of the children will affect the number of hours one of you has to work, or seek to work. If one of you is disabled, that too will have an effect.
However, the ceiling is an either or ceiling. If one of you can get work that pays enough to lift you above the equivalent value of the 'conditionality', then the other will no longer be subject to it.
So:
2x£6.19x35=£433.30 per week.
But, if one of you earns £12.38 per hour, then you would only need one of you to work, because
1x£12.38x35=£433.30
If one of you were very lucky to be earning a wage of £30 per hour, then you would need only one of you to work 15 hours per week.