A very big issue in America today is Gay Marriage. However, if 'marriage' and 'civil union' are different according to law, than this becomes an issue for churches or mosques to deal with on their own. A civil union would be a lifelong legal binding union between two or more people for the purposes of grouping wealth and income and creating tax benefits. Such Unions would have nothing to do with sexual relationships and could be made of as many 'partners' (used in a business way). Marriage would then not be a civil issue at all. It might be beneficial for a married couple to unionize their marriage legally. The tax benefits and child benefits would be enormous.
Finally, the same process for divorce would be applied to a civil union in terms of the dividing of properties.