I don't think so

Matters of the heart …. and life tests …

Yes but it takes work and not just one sided. You both have to agree on a happy medium and if not then things may not be so happy after all.

Sure, but it takes two people who want to try to make it better, not just one.

Yes. Marry someone who is the MOST LIKE YOU.
Have the same values, and the same comforts, and the same interests but most of all marry someone who LIKES YOU; you as in YOU, not a fantasy woman, not a mother, not a wife, not a anything. Marry someone who LIKES you.

Nope but they can be repaired, every one is unique and set in there own ways of doing things, a long with that they also expect certain things from others that may be illusional, the key is to be honest , open and to speak to each other.

Yes, it depends on the two individuals in the relationship. If this relationship consist of understanding, compassion, caring and trust, then there can be love and harmony. These ingredients with many more come natural establishing a foundation for a lasting relationship as individuals and as a couple. However, all things need nourishment, so will this relationship.

Yes.

If both parties are willing to set aside their selfish desires and focus solely on the emotional, physical, and social needs of their partners.

If both parties are focusing on the needs of their partner, then both will be fulfilled. The problem is finding two selfless people in the first place.

The reason you date is to meet people and get to know them. When you find someone that you have so much in common with then you only date them and talk about everything there is to talk about. Kids, family, future, friends, money, bills, everything that could ruin a relationship. Some think that they have to have sex before marriage to hold the guy, WRONG, if the guy really loves you he will only be to grateful to wait, not happy about it, but will understand that it is a good idea. The more you know about a person the less likely the relationship will end.

You can minimize the chance of being unhappy by asking really good questions before marriage. But the truth is that once you create a child – sometimes people change for the worse. And sometimes they change knowing full well that with a child in the mix, they can get away with a LOT of stuff that their partner would NEVER tolerate if there was no child.

For instance I KNOW a bunch of questions I could have with a woman to get a sense of how similar she is to my current wife. My current and only wife til death do us part is GREAT. But I was a little lucky getting her. Now I know a lot more stuff. I will tell my children this before they pick mates. Still – they may not listen.

Yes I believe that unhappiness in marriage/relationships can be avoided. Getting to the point of unhappiness/or being unhappy in any relationship takes time to develop. Recognizing the signs and symptoms, are just as important as recognizing signs, or evidence of cancer.
Unhappiness is like a cancer in any can of relationship. Knowing how to act when difficulties arise, and acting appropriately are paramount.
When opportunities to act are missed, there has to be resolution which brings neutrality, in the place of distortion(s); an immediate resolution, not something that is put off for later on.
It's just unfortunate that, ones who find themselves unhappy in their marriages, and/or any relationship involving people. Lack the knowledge, experience, and sometimes the willingness to do whatever is necessary to restore peace and respect.