Marriage is a lifestyle choice and human beings sometimes make mistakes. It is unrealistic to believe everyone (chooses) the "right mate" for themselves and it makes no sense to continue going down the (wrong) path once you realize you are heading in the wrong direction. Mistakes require correction.
The number one reason for divorce is selecting the wrong mate. We do this when we have not figured out who (we) are yet. One has to do some serious introspective thinking to determine what they want and need in a mate for life (before) they pursue a committed relationship. To do otherwise is the equivalent of going shopping without a list!
Odds are this person's relationships will come about through happenstance and "impulsive connections". This leads one to later attempt to change their mate into the kind of person they (really) want. You're better off trying to find someone who (already is) the kind of person you want to be with. Everyone wants to be loved and accepted for who (they) are.
The second reason why many marriages fail is because they got married for the wrong reasons. They hit an age goal, all of their friends were married, someone was given an ultimatum, there was an unplanned pregnancy, they were simply tired of being single or someone was about to be shipped out for military duty and they wanted to have someone waiting for them.
A marriage based upon circumstances rather than love is likely to fail.
Lastly every healthy person with some measure of self-esteem has boundaries or "deal breakers" which means they are not going to allow others to mistreat or abuse them. This may entail cheating, verbal/physical abuse, sexual abuse, drug addiction/alcoholism, child abuse, overly jealous or possessive behavior, or the recognition that you no longer want the same things for the marriage.
A divorce when it is all said and done is nothing more than a public admission that a (mistake) was made in the mate selection process. All marriages and relationships are "at will". No one is "stuck" with anyone!
"Never love anyone who treats you like you're ordinary."
- Oscar Wilde
Life is a personal journey. We get to (choose) our own friends, lovers, and spouse. A commitment is not a prison. It's an agreement between (like minded) people. There is no amount of "communication" or "work" that can overcome being with someone who does not want what you want. We're either "growing together" or "growing apart".