As they prepared for a future together, the couple barely discussed a subject that, under Saddam Hussein's rule, amounted to a footnote in matters of the heart: He was a Shiite Muslim; she was a Sunni Kurd.

But now those labels are tearing the couple apart. Barred by their families from marrying anyone outside their own sect, the couple has erased one another's cell phone numbers and stopped speaking.

"There is no hope in this country anymore for Sunnis and Shiites to fall in love," said Husham al-Gizzy, the 25-year-old engineer, as he buried his face in his hands.

For decades, marriages between Sunnis and Shiites in Iraq were as ordinary as the daily call to prayer. But the sectarian warfare gripping the country has created a powerful barrier to such romances.

Married people have filed for divorce rather than face the scorn of neighbors. Engaged couples have split up as a result of death threats. And, increasingly, young single Iraqis have concluded it is easier to stick to their own kind when it comes to love and family.

In a country where intermarriage was long considered the glue that held a fragile multi-ethnic society together, this romantic segregation of Sunnis and Shiites is more than just a reflection of the ever more hate-filled chasm between the two groups. It is also a grim foreboding of the future.

"Everyone is just taking sides to prepare for a big civil war," said Adnan Abdul Kareem Enad, manager of Sot al-Jamayaa, a radio station that has aired tales of star-crossed lovers. "You can see the polarization of Iraq in the tensions between Sunnis and Shiites in marriage and dating."

The new taboo on Sunni-Shiite romances is only one of many impediments to love in this war-ravaged country. Religious authorities have forbidden casual dating. Women fearful of the bloodshed have become prisoners in their own homes. Couples have shunned posh restaurants once filled with lovebirds because they fear suicide bombers or kidnappers.

"This is the age of cell phone love," said Omar al-Azzawi, 33, an Internet cafe owner who has a Sunni father and Shiite mother. "If I marry someone, we'll have to get married on the phone."

For Hameed Ayad, a 24-year-old Sunni, the disintegration of his engagement to a Shiite classmate came swiftly after the 2003 U.S.-led invasion. His betrothed shocked him by expressing newfound pride in once-suppressed Shiite customs such as public self-flagellation and pilgrimages to the holy cities of Karbala and Najaf.

Ayad accused his fiancee of fanaticism and broke off the relationship. But to hear him describe Shiite Islam as a "backward" religion suggests that he, too, has sided with his own.

"Even if she were the last woman on Earth, I wouldn't marry a Shiite," said Ayad, a recent graduate in business administration from al-Turath University.

Like many young Iraqi men, Ayad is so busy just trying to stay alive that he has given little thought to dating in the past three years. "I cannot guarantee my own life," he said. "How can I get married and be responsible for others?"

For young Iraqi women, the isolation is often more extreme. The relentless carnage in the city so petrified Areej Abbas, 25, that she did not leave her home a single time for more than three years. She had no cell phone. No friends. No guests. "I was miserable," she said in a Sot al-Jamayaa studio, where she started working as a science show host this month in her first venture out. "I probably would have committed suicide if it weren't for the satellite television."

Universities may be the safest place for a romantic rendezvous, though Shiites have begun to infiltrate campuses such as Baghdad University, posting signs warning of the evils of dating and promiscuity.

But even if soul mates find each other on campus, sectarian differences can quickly split them apart. Many young people say it is parents who are driving a wedge between members of mixed couples.

Samar Hussein, now a 27-year-old Shiite civil servant, said her parents initially rejoiced when a Sunni classmate asked for her hand in marriage four years ago. The family cared little about religious affiliation.

But Hussein's family now worries about the practical considerations of intermarriage. Vast swaths of Baghdad have become no-go zones to members of certain sects. Those who do venture there face abduction or death. "If a Shiite gets married to a Sunni guy, how will her mother be able to go and visit her?" Hussein asked.

Hussein's parents forbid her to see the Sunni man, but she continues to trade covert I-love-you's with him on the phone. She hopes their families might one day change. "We will leave it up to God," she said.

Many couples — particularly well-educated, secular city-dwellers — continue to intermarry. But even when parents consent to the marriage, mixed relationships are often fraught with danger.

Qais Jassim, 26, a Shiite from the Adhamiyah section of Baghdad, spent his wedding night petrified that his Sunni wife's relatives would abduct and behead him. After three months of meetings with the woman's father, Jassim had finally persuaded her parents to support their marriage. But her cousins disagreed. "Leave her alone or we'll kill you," the cousins screamed at him, Jassim recalled.

•Some young Iraqis have tried to connect via ubiquitous Internet chat rooms where, like almost everywhere in Iraq these days, one of the first questions is often: Are you Sunni or Shiite? Give the wrong answer, and the conversation ends.

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