Quasi-affinity

QUASI-AFFINITY. A term used in the civil law to designate the affinity which exists between two persons, one of whom has been betrothed to the kindred of the other, but who have never been married. For example, my brother is betrothed to Maria, and, afterwards, before marriage he dies, there then exists between Maria and me a quasi-affinity.
     2. The history of England furnishes an example of this kind. Catherine of Arragon was betrothed to the brother of Henry VIII. Afterwards Henry married her and, under the pretence of this quasi affinity, he repudiated her, because the marriage was incestuous.