I see two questions being asked on this post. First is an epistemological question: can I know God’s will? The second question is more axiological, namely, how does that knowledge affect my relationship with a “jerk”? Although God not not revealed everything about Himself, that does not mean that I can’t know something about God. God has revealed what he wants us to know about Him through the Scriptures. If we don’t accept the Scriptures as being our epistemological authority, then we are left to our own imagination and/or superstition. We know that Scripture teaches that marriage is to be a life long monogamous heterosexual union. Anything short of that is contrary to God’s will. Divorce is the result of sin or the hardness of our hearts. Because of sin, God allowed the state (civil law) to issue a divorce for two reasons: adultery and desertion. Before you get married, keep your eyes wide open, and after you get married keep them half shut. People get married for the wrong reasons, and they all too often fail to understand what it means to be married. The person that you married was a jerk before you got married, so what did you expect?
Indeed, one of the biggest reasons the Lord YHVH sent us His Word was to let us know what is His will, and what is not His will.
We know the will of God when we know the scriptures.