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.