how should the Church handle so-called "same-sex marriage" vs. divorce?

In response to this video (h/t: SJ)
http://m.crosswalk.com/video/why-marriage-defined-only-between-a-man-and-woman.html


A few thoughts:
-God defined it that way, as she notes, "in the beginning".
-God continues to define it that way, as an ideal.
-But in a fallen world, God allowed all sorts of things with respect to marriage-- most notably, "levirate marriage", where polygamy was often commanded.
-So-called "same-sex marriage" is more of a violation of Webster's Dictionary.


Two big "policy" questions:
-What should missionaries do when people come to Christ in a polygamous culture?
-Given Kassian's argument, why haven't believers and the Church said more about the institution and practice of divorce in the last few decades, which causes far, far more damage-- both in its frequency and its damage to children?


I Corinthians 5:9-13 indicates that sin in the church is worse than sin in the world. Matthew 18:6 indicates that two adults messing with children is worse than two adults messing with each other. Justice indicates that people forcefully messing with others is worse than people engaging in mutually agreeable but sinful activities. 

I heard a Sunday School lesson on Luke 15 (a few weeks ago at WRBC) that got me thinking about how we deal with sin differently when it relates to "the other". Part of the genius of Lk 15's trio is getting us to think about "sinners" as lost, valuable and personal. Generalizing about the (theologically conservative) Church's response to divorce, abortion, and homosexuality: Seeking to balance grace and truth, perhaps we handle D better than A better than H, since we're more likely to know someone who has D more than A more than H. 

Which is less consistent with the heart of Jesus: people making less-than-ideal commitments-- or breaking an ideal commitment, backed by an oath to God and promises to others which does harm to the institution of the commitment and often does great harm to children?