40 years ago, California became the first state to allow people to get divorced simply because they no longer wanted to be married to their partners. In 1969, the California Legislature decided that the then-existing concept of "fault" created more problems that it solved; it felt that making the parties lie to rid themselves of a mate made little sense - no marriage was better than open hostilities, and, besides, court rooms are pretty poor places to decide which spouse was worse, or whether bad conduct had happened at all. Since then, 48 other states have followed suit, leaving only New York without a similar option. That may soon change.
This recent op-ed piece in the New York Times summarizes the arguments for and against no fault divorce now being debated in the New York Legislature. These are issues that create substantial debate, but eventually the result always seems to favor allowing people to divorce more freely; I presume that, ultimately, the majority of politicians want to keep their own options open.
Whether you agree or disagree with the concept, you or your spouse can obtain a divorce simply "because...." In California, the standard is that there be "irreconcilable difference." It is sufficient that one wants a divorce and the other doesn't - such a difference is probably "irreconcilable." California also permits divorce because of "incurable insanity," but in 35 years of practicing family law in San Diego, I've never seen anyone bring such a case. It is too easy to prove that at least one of the parties in the marriage is unhappy and wants out.