english to latin translation

I'm going to assume you meant "...until you're happy."

Felices non sumus donec felix es.

No, I actually meant, "We're not happy until you're not happy." It's a phrase used by airline customers to describe the service they perceive they receive. That's why the two negatives.

Ah, I see. One more question: is "you" singular or plural?

I'm thinking grammatically it must be plural because it is the non-specific general usage that I wish to capture.

Felices non sumus donec felix non estis.