There is a great book called Gay Marriage: Why it is good for gays, good for straights and good for America (http://www.amazon.com/Gay-Marriage-Good-Straights-America/dp/0805078150/ref=sr_1_1?ie=UTF8&s=books&qid=1226033839&sr=8-1) that argues that using the same term means you hold everyone to the same standards. Everyone knows what is expected of a spouse as a commonly accepted social contract and that helps people understand each other.