@dsaf09vasl: They never really go into that too much; it's just said early on that households with them in it experience 'good fortune' (in the business/monetary sense apparently).
Urgh. Super tragic.
And it could have been avoided if they just ... told them that, instead of dramatically intoning "IT'S FORBIDDEN"
Maybe they could have made it work - the two of them with two brides. OR, the two of them with one bride. Hmmm. Oops, derailed my "sad" comment.