Are you normal when it comes to love, sex?

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(CBS News) Two top sociologists have teamed up with a wellness specialist to help answer common questions about what constitutes "normal" behavior in romantic relationships. In a new book, they offer a glimpse behind closed doors of happy couples and promises to help everyday couples apply the practices of what one co-author calls "extremely happy couples."

Pepper Schwartz, a Yale sociologist and co-author with Chrisanna Northrup and Harvard sociologist James Witte of "The Normal Bar: The Surprising Secrets of Happy Couples and What They Reveal About Creating a New Normal in Your Relationship," said one basic yet critical factor in relationship success is "the affection [happy couples] give each other in little ways: hugging, kissing, [saying] 'I love you' every day...holding hands, public displays of affection."

"We really need a lot of fuel for our relationship," Schwartz said Thursday on "CBS This Morning."

In their research, the co-authors gathered information from nearly 100,000 people and found that without taking age into consideration, extremely happy couples report they have sex "three to four times a week." But Schwartz was quick to add, "If you're 50, it's a couple times a week."

I think the idea is that they feel that way about each other," Schwartz continued, "Not that that's some kind of standard everyone has to do but they've got that connection."

And despite the common stereotype that women push for better communication and men for more sex in their relationships, Schwartz explained that in reality, men and women both feel the need for more communication.

"Everybody said communication because in fact if you're not talking well, if you can't talk through things together, everything goes downhill," Schwartz said.

Speaking to the commonly-held notion that the "seven year itch" kicks in after the first few years of marriage, Schwartz said there is typically a shift in attitudes within a marriage "six to nine years in," and explained it is not necessarily "an itch to go outside" the relationship, but more likely an itch driven by the point at which "things start to get habituated" and "people stop working at their relationship."

"So I think people know when that kind of thing might start to grab the relationship...that would be the time to re-up and start to remember all those things you used to do when you were courting," Schwartz said.