In America right now, there is a lot of a talk about "changing the definition of marriage".
The last time our country changed the definition of marriage was in the 1950's, when "no fault" divorce became legal. (A no fault divorce is one in which you can get a divorce, without needing to prove anything.) The idea was that easy divorces would end absuive relationships and improve marriage as a whole. That is certainly a praiseworthy goal.
"A lifelong commitment" was dropped from the definition of marriage, and the results were shockingly bad. Divorce didn't improve the institution of marriage; divorce practically destroyed it. The 2010 census tells us that 44% of all children are raised by single parents, not married parents. Today, marriages with divorce are more common than marriages with "to death do us part"; the current divorce rate is over 50%, with the majority of marriages ending after 1-3 years and 18-20 years.
On one hand, I'm extremely reluctant to change the definition of marriage again, because the last time we changed it was such a huge disaster. On the other hand, changing the definition of marriage again could be a good thing, provided that the new definition makes marriage more stable and beneficial to society.
I guess what I'm trying to say is that America's current definition of marriage is clearly flawed (and false). We should change the definition, only if the new definition is an improvement. If a proposed new definition is worse than the one we currently have, I don't want it.