Her relationship has given her the freedom to be herself, vices and all. She's the occasional drinker and smoker, and doesn't wear a hijab. Instead she sports her natural black hair, often pulled back in a frazzled ponytail. She's Razzan Nakhlawi, a liberal, British Muslim who's been dating an American agnostic man for almost two years.

Reflecting on her inter-religious romance, taboo among more-orthodox Muslims, Nakhlawi sees inter-religious relationships as a way to cultivate a religiously-tolerant society.

The "U.S. Religious Landscape Study," conducted by the Pew Research Center between June and September 2014, found that interfaith marriage in America has increased by almost 40 percent since 2010. Only 20 percent of Americans were wed to people practicing other religions before 1960.

Rev. Jim Burklo, who has been the associate dean of religious life at the University of Southern California for eight years, said American society is becoming increasingly religiously diverse and tolerant. He cited the book "American Grace: How Religion Divides and Unites Us" by Robert Putnam and David Campbell, which is based on two comprehensive surveys about religion and public life in America.

Additional Pew data found that one-fifth of adults in the United States were raised with a mixed religious background. These findings suggest America's increasing religious tolerance has a connection to interfaith unions and families.

A prime example is Nakhlawi's relationship with her boyfriend, Cameron Hejna.

Hejna, who grew up Catholic, is a junior at USC studying music composition. Nakhlawi, a journalism major, said Hejna has become more religiously tolerant and aware since they met. Before, he couldn't even separate radical Islam from mainstream Islam.

"He knows a lot about Islam at this point and does his research," Nakhlawi said. "Now he's more vocally supportive of Muslims and Muslim women."

But Rev. Buklo said that this increasingly accepting atmosphere in America is also related to the fact that people are to different religions, whether through work, school or friends.

Burklo hasn't just read about this phenomenon, he lives it. He's officiated at interfaith marriages, followed their successes and failures, and seen how the couples' love has strengthened inter-religious community ties. Burklo himself is in one of these marriages.

"She adores me and admires my religion," he said talking about his wife, Roberta Burklo.

He playfully described her as a "recovering Catholic" because she has strong Catholic values but doesn't completely practice her religion.

"She's the dream minister's wife," he said.

He describes himself as a liberal Protestant under the United Church of Christ and has been a pastor for three churches since 1979. He describes Roberta as someone who's "warm, calls people when they're sick and feeds people." She doesn't attend all of his religious services and he doesn't expect her to. This mutual respect and understanding explains why the Burklos have been in an interfaith marriage for 22 years.

The reverend has seen first hand how interfaith marriages can work and what the results of this kind of romance can be. He's also seen how these relationships can influence the community.

He says these marriages can succeed from the beginning. This would require each person to be vulnerable and honest with their expectations and to thoughtfully discuss the issues that may lie ahead while balancing two religions.

Some of these issues include having to deal with unaccepting family, raising of children, creating a harmonious kitchen if a partner's religion has dietary guidelines, making medical choices and accepting how much time a partner needs to practice their religion.

Burklo has performed marriages between an Afghani Muslim and an American Protestant, a Hindu and a Christian, a Catholic and a Scientologist, and a progressive Christian and a Thai Buddhist.

A couple could start experiencing issues even before the wedding, Burklo said. For example, which religious institution will officiate the ceremony and how will religion be integrated into the marriage ceremony; in extreme cases, dealing with a religious identity crisis.

"I meet with a couple before marrying them and in between the first and second time meeting with them, one of the two people all of a sudden becomes super religious," Burklo said. "Suddenly they're practicing their faith in a way they weren't practicing it before all because they're marrying someone who doesn't practice it."

Some of these issue stem from the fact that these relationships are taboo in some religions.

Imam Suhail Mulla of Orange, California, has performed interfaith marriages between Muslim men and Christian or Jewish women but refuses to officiate marriages between a Muslim woman with someone outside of Islam.

Muslim women are not permitted to marry outside of the faith, but Muslim men can marry Muslims, Christians or Jews, he said.

Mulla still believes marriages between two Muslims are best.

"You need someone in your own household that's going to uphold your Islamic value system and not someone who's going to subtract from who you are and what you believe," he said.

Mulla said inter-religious relationships work best with people of a faith who are non-practicing or who are "weak in faith." He doesn't believe romance can overcome these differences.

But Razzan Nakhlawi and her boyfriend Cameron Hejna show that love can conquer some, if not all, conflicts between religious ideologies.

Correction: Originally the author misspelled Cameron Hejna's last name as "Henja."