There are plenty of potential marriage partners. Usually, dating relationships spring up in three different settings: first, by meeting other people in the same community. But there are never very many potential partners living in the same neighborhood. My young friend had a point. In New York City, it is not uncommon to be strangers with people who have lived down the hall for the last twenty years. Secondly, couples sometimes develop dating relationships at work. These are usually discouraged by employers, but take place anyway. After a certain age, however, many of the other workers are already married. Third, and probably most important, couples meet each other during shared activities, such as academic studies, or sports, or organized social activities, or at church. Having a particular interest makes someone interesting to someone who shares that interest. Nowadays, of course, there is internet dating.