My feeling is that they were not meant to be together. I don't think it has much to do with whether they were meant to be or not. Most people who get married do so because they love each other and want to be together. Still, about half of them don't make it. Women are the ones who make or break the relationship.
Men are much easier to satisfy.
In fact, it was kind of interesting that they took one hundred couples and asked them all how satisfied they were with their marriage. So, clearly, women have higher standards and are more demanding of their relationship. It's women who want more and who see the possibilities. It's also the reason that two out of three times it's her that's asking for things to be better. If she's able to ask for change in a way that works, then things get better and both of them will benefit from those gains, but if she isn't able to ask for change in a way that works, then she makes him feel bad and it will bring out his worst.