But this idea is terribly inaccurate. Strong romantic matches do not happen by accident; good men attract good women, and vice versa.
Perhaps the concept of "luck" in relationships would be true in an era where arranged marriages were common and courting couples did not choose their spouses based on “love.” (Although even in such an era, parents would seek to match their children with suitable mates, and so would have an incentive to match their children with virtuous partners.)
But in an era where relationships are sparked by romantic interest and tested through the sweet trial of dating, luck has very little to do with the formation of stable romantic relationships. People freely choose their partners in romantic relationships, and their life choices shape their choice of romantic partners.
Humans tend to marry on their own level. An intelligent man will usually seek an intelligent mate. A wealthy man will most likely look for a wealthy mate (Cinderella stories notwithstanding). Strong Catholics often seek out other strong Catholics.
So too do virtuous people seek out virtuous partners. We seek partners in our relationships; we do not seek those we can bedazzle continuously as worthy mates for life. And though a dating or married individual may speak of his or her partner as a “better half,” instinctively he or she recognizes that he is worthy of the other’s love, that he or she is a suitable match for the other person. A relationship founded on fundamental inequality is a precarious one.
Yes, there are caveats and exceptions to this rule. Men and women do seek out partners who exhibit good qualities they lack. Yes, women do tend to “marry up” regarding financial and social status (although this is increasingly being called into question in an increasingly feminized society). But these caveats are largely incidental concerning each partner's level of virtue.
This is comforting – and cautioning. For if a man lives a life of virtue, the chances are very good that he will end up choosing a woman for a spouse who also exhibits similar virtue - and will be happier for his choice. But if he fail to exhibit virtue, the reverse is likely true - and he and the relationship will suffer as a result..