However, scientists believe they have developed a test which could give a good indication of which unions are doomed to failure.
The team from Ohio University in the US has spent ten years developing the test.
The scientists took samples from 90 married couples and then went back to them ten years later to find out which ones were still together.
They analysed the samples for levels of the hormones epinephrine (adrenaline), norepinephrine, ACTH, and cortisol. All these chemicals are involved in the process of preparing the body to deal with confrontation.
Levels of three out of four of the hormones were consistently higher in couples who divorced.
Women
The differences were most pronounced in women.
Lead researcher Dr Janice Kiecolt-Glaser said: "The literature suggests that behavioural matters, such as negativity or aggression might be the best predictors of divorce, but we found that the best predictors of all were hormone levels.
"The data show that women, in particular, register much higher levels of stress hormones, like epinephrine, than men do, in times of conflict.
"These higher levels of stress hormones do not go away. They stay elevated during more routine interaction, and are even elevated at night, when they are sleeping."
Dr Kiecolt-Glaser said the individuals with elevated hormone levels were not necessarily hot-headed in general.
"It's not genetic, as far as we can tell. It looks like it is simply a reaction to the presence of the spouse."
She said that couples who later divorced thought that they were as happy when they first wed as couples who stayed together.
"They were very happy in what they were saying, but what their hormones are telling us is that some part of them was very uneasy.
"Listen to your gut. It may be telling you something."
Approximately 40% of UK marriages end in divorce.