One of the tools I use the most often in helping couples prepare for marriage is the Taylor Johnson Temperament test. For very little money, a couple can determine how well they know each other PLUS know how compatible they are together. I have administered this test over 200 times and I am yet to find someone who didn’t glean something to help their relationship.
There is no reason to be nervous about the results either. No one fails the test. The only bad that can come from it is not doing it.