Should the length of a marriage determine the "success" of it?

Many of us are wired to believe that the longer a marriage lasts, the more successful it is. (The courts certainly give a greater “respect” to a long term marriage than a short term one. And by that I mean that a spouse in a long term marriage has a greater chance of getting 50% of the marital assets after a split. Not true with a shorter marriage.) 
But is it necessarily true that a marriage that lasts longer, is a more “successful” marriage? I mean, think of your marriage as a sort of political regime. Just because a regime lasts a long time doesn’t necessarily make it successful. It could be hell on Earth for a lot of people, actually.
Many women from earlier generations remain married for fifty years or more, practically their entire lives, only becoming “free” upon the death of their spouse. But if you speak to a vast number of them, the marriage was not necessarily a happy one.
This leads me to wonder whether “happiness” is really relevant in a marriage, for one thing. For another, I wonder whether the success of a marriage should simply be based on whether it lasts and for how long it lasts.
Because, what is so successful about living a lifetime of misery with someone who brings out the worse in you, or someone whom, in the end, you do not love? Can a loveless marriage be successful? But then again, does love have anything to do with it? What’s love got to do with it?
Without question, marriage is intended to be a commitment. It is a contract between two people. An agreement. A stipulation. A promise. A vow. It is also described by many as an institution.
If we think of marriage as a “contract” Is a successful contract one that runs its course? Where both parties do what they say they are going to do? I think I would have to answer yes to that – as a general rule. But what if along the way, for whatever reason one or both of the parties realize that they can no longer meet the obligations in the contract? And they decide to terminate the contract? Is that failure? Would it be “success” for them to keep the contract binding even when, for one reason or another, one or both parties could no longer fulfill his/her obligations?
Or would “success” be more of the handshake that says, you know what? It was a nice ride, but this is not working anymore and we need to agree to break this “agreement” to preserve our relationship.
What am I talking about? Gibberish, that’s what. Forget everything I just said. I’m sleep deprived. I will revisit this subject when I am more awake. But think about this. Is a long term marriage necessarily a successful marriage?