Per the 2010 Census, married couples now represent only 48 percent of all U.S. households, compared with nearly 75 percent as recently as 1972.

The outlook for modern marriage seems to have gotten dramatically worse just during this first decade of the new millennium.

In fact, it now appears that the "institution" of marriage as we know it may be in danger of coming to a fairly abrupt end in modern day America.

I surprised myself by arriving at this rather startling conclusion while researching the most recent social and demographic material for the fourth edition of my book, "Divorce with Decency." The marriage rate in America has been in severe decline since at least 2004, with the steepest drop-off having begun in the 2004-2006 time frame — and plummeting sharply ever since.

America’s views on marriage now seem to be changing incredibly rapidly, and the rise of civil unions could be yet another straw that helps "break the back" of conventional marriage.

The potentially adverse impact of the unintended consequences of heterosexuals now starting to prefer the seemingly less stodgy, complicated and formalistic civil union/domestic partnership formats (originally fostered by homosexuals) — instead of the more traditional legal, formal, conventional, constricting marriages — cannot be overstated.

The battle for the legal recognition of civil unions and all their attendant rights and benefits originated as an extension of basic civil rights to homosexuals. But once in place, there is no way to deny the civil union option to heterosexuals as well.

From a strictly practical standpoint, the main legal goal of the civil union/domestic partnerships movement is to procure "reciprocal beneficiary" rights and status in order to be able to place one’s "partner" on the same medical, insurance, financial and/or retirement plan(s) as the dependent/alternate payee, etc.

Essentially, it is to gain many of the institutionalized bonuses/benefits that governments, corporations, etc., offer to their citizens/employees, but without much of the perceived humbug, hassle and formality of traditional marriage.

I suspect that in the future a lot of Americans, both gay and heterosexual, may opt for that format.

In Europe, where civil unions have been available longer, they are now becoming more popular than traditional marriage.

Personally, I am a big fan of the new civil unions law and it is by no means my intent to criticize the liberating effect of the legislation itself.

Rather, my focus as an author and observer of social trends is on its possible unintended consequences.

Simply put, the rise of the civil union option could ultimately — and inadvertently — help accelerate the decline and fall of marriage.

This could be a biggie. Stay tuned.

Honolulu divorce attorney Bradley A. Coates is the founder of Coates and Frey, Hawaii’s largest family law firm, and the author of "Divorce with Decency."