Why does it seem like relationships don’t last long anymore?

Well there's zero context as to what could of lead to a divorce in this, but a few common issues thst can kead to divorce in long term relationships are: Lack of intimacy, people changing throughout the decades or someone could have cheated. It could be as simple as the couple no longer being happy or content with each other. These factors, combined with the destigmatization of divorce means it's often easier to part ways and either become friends or just have nothing to do with one another.