Kentucky is one of the few remaining states to recognize dower and curtesy. Dower arose in common law as a way to provide security to a married woman who could not legally own property, but may outlive her husband. Likewise, curtesy is a surviving husband's interest in his late wife's estate. For these property rights to arise a couple must be married and the owner spouse must pre-decease the non-owner spouse.
KRS 392.020 establishes dower and curtesy as statutory rights; KRS 392.080 allows a surviving spouse to elect against the decedent spouse's will and entitles them to a one-third interest in the real property of the decedent spouse. This creates potential estate planning problems, as the pre-death intent of a spouse can be superseded by statute, and left to the whim of the surviving spouse.
If you do not want your property to pass to a spouse take extra steps to make your intentions clear. Consider placing the property into a trust or including it in an ante-nuptial agreement.