Bella DePaulo, Ph.D., is a project scientist and social psychologist at the University of California, Santa Barbara. While speaking to the American Psychological Association, she pointed out an interesting fact: with all of the celebration of marriage and coupling and weddings, you'd think that married people would be happier. But if you were to follow the same people over the course of their lives and ask them over and over again, "Are you happy? Are you happy? Are you happy? How happy are you?", you'd see that when people get married, they end up no happier than they were when they were single.

So if someone is a really happy single person, they'll probably be a happily married person and if they were not so happy as a single person, they probably will not be so happy as a married person.

"Sometimes, people get a little bump in happiness [at the time when they tie the knot], but then they go back to being as happy or as unhappy as they were when they were single," DePaulo said.

"And here's something else about that newlywed effect – that little increase in happiness around the wedding – it only happens for the married people who get married and stay married. If you're one of those married couples who's going to end up divorced, as your wedding is approaching you're already getting a tiny bit less happy."

So there you have it: happiness starts from within. And getting a partner isn't going to change that. Consciously or not, people are probably realizing that. The number of single-person households in the United States has been growing steadily since 1960.

DePaulo has been studying people who she calls "single at heart." They're the ones who live their best, most authentic, most meaningful lives by staying single. "When you ask [these people] ... what they think when they know they're going to have some time alone coming up, overwhelmingly, more than 95 percent say they look forward to it, they really savor their solitude. And they don't worry – or they very rarely worry that if they have time to themselves, they're going to feel lonely."

According to her, loneliness is a really important thing to study. We need to be more aware of what people can get out of solitude rather than just worrying about people who are going to be lonely.