Translation:Your husband has not been in this country.
I tend to take a preterite as referring a definite time, i.e., "Your husband was not in this country" at the particular time we have been talking about. That is very different from "Your husband has not (or never) been in this country." Duolingo accepts both, but does the P really mean either, depending on context? Every Romance language handles this tense-aspect distinction differently.
I agree, and I also feel the preterite has more of a sense of finality than duolingo is giving it. For example, couldn't this also be translated as "your husband was never in this country"? I feel a different construction would be necessary to illustrate his never being in this country being relevant to the present - e.g., "o seu marido nao tem estado neste pais". Thoughts?