Salmo,

"No person can know, with absolute certainty, that the person they are considering marrying will not turn into an abusive or intolerable partner." Maybe not 100% but there are ways to reduce the chances significantly. One thing any seasoned crime investigator will tell you is application of Occams Razor solves in the high 90% of most cases. It is true for other areas of life as well. I am sure you are familiar with it.

http://pespmc1.vub.ac.be/OCCAMRAZ.html