Ed Friedman, a family therapist and well known religious leader, now deceased, was known to say, the people who date and the people who marry bear no resemblance to each other. The best it is going to be is in the courtship. That is when couples normally put their best foot forward.
Therefore, if the courtship is rocky, marriage is not going to improve it.
That having been said, it isn’t likely that changing the partner will change bad habits.
People fight for a variety of reasons. Sometimes they fight because they grew up with conflict and don’t know anything else.
They are just copying styles they know.
Sometimes conflict gives people distance from intimacy. When it is functional in this manner the issue of fear of intimacy must be dealt with—address the problem not the symptom.
So, like any problem solving the problem needs to be resolved in order for the relationship to work well.
Most simply, people with bad habits fight to prove they are right. It is impossible to maintain a relationship and be right at the same time. People need to learn to fight to find out what they are doing wrong. Most people fight to be right.
I say to my husband, "let’s do it wrong. Let’s do it my way!"
The relationship requires negotiation.
Fighting to win shuts down the conversation.
There are those people who fear getting too close to another person. What they fear is that their own imperfections will be revealed, that the partner will then be disappointed, and that they will then get left.The conflict keeps the partner at a safe distance and away from seeing the imperfections of the person creating the conflict. Sometimes both partners share the same fears so both are invested in keeping conflict going.
The fighting problem must still get resolved.
It should be resolved BEFORE any permanent arrangements are made.
People who come from divorce often don’t trust relationships. They may struggle against émersion in it much like swimmers learning to swim fight the water. This is the surest way to sink and drowned.
Fear of intimacy is also seen in infidelity. Having secrets dilutes the primary relationship. When we have secrets we hide from our partner to protect the secret. People who suspect a lie will fight to get to the truth just as the person lying fights to protect the revelation of the truth.
In the question, "Should couples who fight in courtship marry?", the answer is not until they learn a better style of dealing with each other as couple partners. Premarital counseling would be in order to work through the difficulties.
There are issues here as well. People on a set course of action are often not deterred. They are often full of oxytocin, the bonding hormone. This makes couples euphoric and they are apt to think that love in couple relationships conquers all. They may start the repair process but not stay with it long enough to make a real difference.
The point is, conflict keeps people apart and results in more problems in the next generation— either resulting in too much conflict or the opposite, children who grow up to be conflict avoidant which is really no better. My advice is to fix the problem before the marriage!