Reading through Genesis and considering recent Supreme Court decisions – Abraham married a second time and sired more children… but also had children by his “concubines” (plural), to whom he gave gifts upon his approaching death. (Gen. 25) No negative commentary on this form of coupling from the biblical record, thus far anyway.
We all like to think God is on our side, don’t we? The demand that God’s definition of marriage must look just like late 20th Century, American, Culture War notions of marriage isn’t faring so well when one actually reads Scripture. For better or for worse, the Biblical record does not support notions of marriage based on romantic love or of one single man and one single woman or on the sanctioning of a centralized State.
The attempts to force Scripture to support what one group or another wants (or imagine God demands) is nothing new.
The profound opposition to gay marriage by certain groups (which is their civic right to do), has caused them to so bend Scripture to support their cause that even a cursory reading makes obvious that their attempts fail – again, for better or for worse.