It might be true that most divorces are caused by one party, but I am not certain.
It seems in this age and culture, that when couples get married for self-fulfillment reasons or love being the primary force, then divorce could be initiated by both and agreed to by both. Many times one party may show bad feelings first, then the other party realizes that the marriage may or may not be worth saving and the two come to a mutual decision.
In this age of marrying and committing for reasons of the heart, thank goodness for no-fault divorce. It is essential.