CreamBun', I actually find what you're saying a bit offensive, definitely patronising and startlingly naive.
The overwhelming majority of people don't go into marriage thinking they're going to get divorced. They think they have the passion, they think they are best friends just like you.
I'm not divorced, nobody in my family has divorced and in my entire extended family only my husband's aunt has ever divorced and that was not her choice. So I'm certainly not trying to justify my own or my families divorces but I have seen it happen and it can honestly happen to anybody.
In fact, my husband's aunt was blissfully happy, had two small children a lovely house and a great marriage. They were the last people that you would ever have imagined would divorce. Her husband was in a serious car accident which she spent years nursing him back from very poor health from. She suffered severe financial hardship and when he recovered she went back to working two jobs because he needed to retrain because he couldn't physically return to the job he had done previously. He had a near death experience which had made him question his life and existence and then when he retrained he started mixing with a different type of person he would probably have never met otherwise and decided that their lifestyle was preferable to his previous one and walked out on his wife for a woman he could have that kind of life with. I'm absolutely certain if he'd never had his accident they would still be married and probably happy because he would never have taken a turn which saw him see a different type of life which appealed to him more. These things do literally come out of nowhere sometimes.
Also, I have to say, I've seen a few women who have had exactly your attitude who have had nasty surprises somewhere along the line. People who are blissfully happy, totally in love and think it's perfect then somewhere along the line they realise that the person they're married to has never been quite as enamoured of the whole set up as they are.
I hate this attitude anyway, the way some people assume that if you get divorced it's somehow your fault or that the people involved are personally defective and somehow not as good or sensible as people who've stayed together. I've seen friends get divorced and people take this nasty attitude and freeze them out of their 'couples' world and suddenly they're not good enough for them anymore or somehow they've 'failed' when often they've simply been unlucky that life has taken them in different directions.
People change, we're living longer than ever so there are more and more opportunities for people to change in ways which will make them no longer compatible. I think you're stunningly naive Creambun to think that you're going to go through life as a blissful couple.
As another poster said, I don't think there are many, if any couples that never go through a sticky patch in which they think their relationship might be at risk. And I would suspect that relationships where one partner believes that they are unshakeable and there will never be a risk to their relationship are quite probably at a bigger risk than many others.