WHEN Bill and Melinda Gates announced they were ending their 27-year relationship, Melinda’s petition for divorce called their marriage “irretrievably broken.”

Over the course of such a long marriage, tension can build up in one of three main relationship categories: incompatibility, infidelity, and irreconcilable differences, also called the three i’s, according to therapist Tess Brigham.

Incompatibility in living, spending, and romantic habits can build resentment over time.

“For most people, money is the top reason why people get divorced,” said Marilyn Chinitz, Tom Cruise’s divorce attorney.

While having different opinions isn’t necessarily a deal-breaker, the inability to compromise and talk about those differences is a huge problem, according to Brigham.

“While someone might say, ‘We couldn’t agree on money,’ what that really means is, ‘We fought all the time about money, my partner never listened to me, they spent money behind my back without telling me,’” she said.

“Another couple might have different beliefs about money, but if they can speak to each other respectively and hear each other’s point of view, then they’re not going to break up over it.”

Infidelity can permanently break trust.

Kari Lichtenstein, a lawyer from New York State, the U.S., said infidelity is one of the main reasons people file for divorce.

Infidelity occurs when one or both partners are intimate with another person outside of their vows, Brigham said.

Adding, infidelity can lead to lasting trust issues in a marriage, which can ultimately make the relationship crumble.

Also, irreconcilable differences, like parenting styles and future goals, are sometimes discussed too late in the relationship.

It’s natural for couples to grow and change over the course of their marriages, but the difference between a successful marriage and a failing one is whether couples grow together or apart, according to Brigham.

A relationship can deteriorate in the early years of marriage if a couple has different opinions on having children and how to raise them, she said.

Differences in how a couple views their individual and joint futures could also come up after their children have left the house.

“Even if a couple makes it through the child-raising years, when faced with an empty nest, they can easily get to the point where the Gates’ found themselves where ‘the relationship has run its course’ and they want ‘something more,’” said Michael Stutman, a lawyer from New York State.

(SD-Agencies)