You don't have to share a reason, but if you do, be honest about it. It's no good saying you can't afford a destination event and then heading to Italy two weeks later. In that case, say that you've made other vacation plans or that you've committed to something else, Post says. Don't say yes and reverse your decision later. It's better to thank someone for an invitation and wait to reply when you're sure.

Post did say that turning someone down for a major milestone "can be very statement-making." She calls weddings, christenings, funerals and other important moments "precedent-setting events."

"It's much easier to carry on a relationship with someone, even if it's a rough relationship, if you participate in the big events," Post said.

Joining friends and family hasn't always been such a big production.

The crossing of states and continents to be part of social rituals has picked up over the past 30 years as more people earn college degrees and participate in a national labor market, according to Alexander. More Americans leave home, go to college and never look back, so friends and family are scattered.

Saying no to traveling across the country for special occasions seems to be getting harder. People used to accept the idea that an event might just be too far away, Alexander says. "Now there's an expectation that there's no excuse," especially within the continental United States.

Cheaper and more accessible air travel, more affordable telephone service and the emergence of virtual communication have all given rise to people coming together more readily from long distances to mark milestones with their peers, Alexander says. People ages 18 to 30 are especially likely to ignore the barriers of physical distance, because they're used to the virtual closeness of daily communication with their friends on social media.

And the most important ties are sustained through rituals.

"It's kind of the opposite of the uncertainty that we all have in our society. I mean, we're all uncertain about our jobs, about our children, about success, about relationships -- whether we're married or not," Alexander said. "Ritual is reassuring and connecting."

Connecting or not, there's still nothing that says you have to attend.

"Anybody that feels they have to succumb to social pressure, whatever it is ... they need to realize the importance of listening to your inner self and developing your inner self," said Amitai Etzioni, a sociologist and director of the Institute for Communitarian Policy Studies at the George Washington University. "It's not automatic that the community has the right of way."

Part of what complicates matters and creates that to-go-or-not-to-go tension is the fact that the social norms that existed before the sexual revolution and the civil rights movement were upended in the late '60s. Since then, everyone's been coming up with their own rules and trying to create unique, distinctive events to celebrate their lives, says Etzioni, who edited the book "We Are What We Celebrate: Understanding Holidays and Rituals."

Weddings used to be "a ceremony, a reception, dinner." Now, some are three-day events.

So many situations today require deliberation and negotiation and often lead to misunderstanding.

"In the olden days, if you went on a date, there was no question, the boy paid. Now, it's complicated," Etzioni said.

"Nothing is etched in stone anymore."

How important are rituals to you? How much are you willing to spend to participate? Share your stories below.