Excerpt from this article:
Loose ties have traditionally played a key role in meeting partners. While most people were unlikely to date one of their best friends, they were highly likely to date people who were linked with their group of friends; a friend of a friend, for example. In the language of network theory, dating partners were embedded in each other’s networks.
Indeed, this has long been reflected in surveys of the way people meet their partners: through mutual friends, in bars, at work, in educational institutions, at church, through their families, and so on.
Online dating has changed that. Today, online dating is the second most common way for heterosexual couples to meet. For homosexual couples, it is far and away the most popular.
That has significant implications. “People who meet online tend to be complete strangers,” say Ortega and Hergovich. And when people meet in this way, it sets up social links that were previously nonexistent.