why does the Western world have the highest divorce rates out of all cultures

Because women in Western culture have more autonomy and options than women in other cultures. If a woman in the US is in a bad marriage, divorce is a relatively easy option. She is likely to have a career/means of supporting herself. Women in non-Western cultures do not have as many options or resources.

There's also a social stigma against divorce in many cultures, particularly religious ones. And Western nations tend to have smoother legal procedures. If a country makes it difficult or impossible to obtain a divorce, that country will have a lower divorce rate.

It's also possible that the divorce rate of Western countries such as the US is inflated by the fact that people are more likely to have multiple divorces. Not sure how much of a difference it makes, but I personally know multiple people who have been divorced twice, so it must have at least some effect on the rate.

I'm not sure it has much - if anything - it has to do with waiting until you're over 27 to get married.