Child Bride or Child Abuse Victim?

Some see 22-year-old Matt Koso as a responsible young man who did the right thing. In May he married his pregnant girlfriend, Crystal, who has since given birth to their baby daughter. But others see a big problem, because his new bride and now mother of his daughter is a 14-year-old girl.

The relationship has generated tremendous controversy in their home state of Nebraska and in Kansas, where they were permitted to wed. "All I'm trying to do is make a living for me and my wife and my child. That's all I'm trying to do," Matt Koso told "20/20's" Don Dahler.

But Nebraska Attorney General Jon Bruning sees the situation differently. "When grown men are choosing to have sex with pre-teen girls, they're breaking the law. And when pre-teen girls are choosing to have sex with grown men, it's a mistake," he said.

Bruning has indicted Matt for first-degree sexual assault.

Crystal wishes Bruning would simply leave her and her new husband alone. "What he's doing is ruining my life. He's not saving me -- saving me, he would have left me alone," she said.

Matt and Crystal have been together as a couple for over two years. Just a few weeks ago, Crystal gave birth to a beautiful baby girl named Samara.

But Bruning doesn't see any upside to the Kosos' romance.

"We need to protect our kids. We as adults make choices for them, choices like telling them, 'You can't drink and you can't drive and you can't have sex with a grown man.' And I have a duty to prosecute grown men who have sex with little girls," he said.

Beginnings in a Child's Friendship

Matt was 16 when he first met the 8-year-old sister of one of his friends. He liked Crystal immediately.

He recalled cheering her up by imitating the voice of "Sesame Street" character Elmo when she was having a bad day, he said. "I got her to smile pretty big. So it kind of brightened her day a little bit," he recalled.

Six years later, Crystal says the Elmo imitation still cheers her up.

The childhood friendship gradually turned into something more. They both say the age difference wasn't an issue.

"I hung out with people that were below my own age group, because I never really got along with the people my own age," Matt said.

By the time Crystal was 13 -- and he was 21 -- their relationship was no longer a secret.

Matt's mother, Peggy Koso, told her son he shouldn't be so seriously involved with such a young girl. "We told him … this is not the right thing to be doing. You need to back off, because she has so many experiences that she needs to go through before she settles on just one person," she said.

Crystal's mother also tried to break up the couple by taking out a protective order against Matt, legally forbidding him to see her daughter. It was largely ignored by the couple and never enforced by local police or any state agency, despite the fact that Crystal wasn't the first young girl that Matt had dated.

Matt said none of those other relationships were romantic ones, but Matt and Crystal did become intimate. "We were just talking and she kissed me. I'd kiss her back. I mean, it was just one of those things that happens when one thing leads to another," he said.

Parents Agree to Let Couple Marry

And like a modern Midwest version of Romeo and Juliet, their forbidden romance set in motion a chain of events that would soon spiral out of control.

Matt said he felt no warning signal at the start of their relationship, telling him that he should keep his relationship with Crystal platonic. Crystal didn't give too much thought to the consequences of her romantic relationship with Matt either.

She said she wasn't sure whether or not the relationship was heading toward sex. But Matt wasn't Crystal's first sexual partner. She said she had had several boyfriends before Matt and had already had sex.

But Matt, as a 21-year-old, was clearly breaking the statutory rape laws of Nebraska, which forbid an adult 19 and older from having sex with a minor under the age of 16.

And things only became more complicated when they learned Crystal was pregnant.

Matt's mother was stunned and upset. "The day after I found out about it, I probably spent the whole day either in bed, on the couch, or in my recliner crying, because I was so scared. I didn't know what we were going to do," she said.

Peggy Koso said she decided that, for Crystal and Matt, the best thing to do would be to get married.

Crystal's mother agreed. But in the state of Nebraska it's illegal for a 14-year-old to marry. So the couple drove to Kansas, where girls as young as 12 can wed with parental consent. On May 3, Matt and Crystal became man and wife.

Thinking they had now solved all their legal problems, they moved into the basement of his mother's home in Falls City, where they set up house with his collection of hundreds of Hot Wheel cars and her love notes, written in crayon, tacked to the wall.

As they waited for the birth of their baby, news of their marriage reached Bruning, an attorney general who's built a reputation for going after child abusers.

Kansas accepts them as legally married. Therefore, the United States accepts they're legally married. Why prosecute?

For Bruning, it's simple. "When somebody has sex with a 12-year-old who's a grown man, you can't suddenly try to fix it by saying, 'Let's go get a piece of paper,'" he said.

Bruning said he sees the marriage as simply a loophole, a way for Koso to protect himself from prosecution.

On Aug. 30, with his daughter just over a week old, Koso was formally charged with sexual assault. He pleaded not guilty and is free on $5,000 bond.

He insists his relationship with Crystal is straightforward love. But he was less clear on whether he would allow his own pre-teen daughter to date a grown man.

"I'm going to protect my daughter … I can't say against guys like me because I'm not a pedophile. I mean, I'm not. I'll tell you, I'll tell you that now and I'll tell you that later. I'm not a pedophile," he said.

But what age would he find it acceptable for a girl to have sex with a man his age? "That to a certain extent is their own decision," he said.

Protecting a Young Girl, or Destroying a Home?

Matt's case has sparked an outcry all across the state of Nebraska and around the country. But the majority of letters that Attorney General Bruning has received say the couple should be left alone and many call him a home wrecker.

Bruning said he's unfazed by the criticism. "These relationships are not equal. Three-quarters of these girls, when they grow up, will say that they were coerced."

Today, Matt and Crystal's lives are in limbo. Their futures are uncertain as they await the beginning of Matt's trial, now scheduled for November.

Matt is hoping for a quick resolution -- perhaps probation -- so he can provide for his family. "One thing's for dang sure," he said. "I'm gonna be the best father I can be. And I ain't gonna treat my little girl badly. I mean, like I said, I'm going to grow up and just give her all I can give."

Is Crystal simply a child bride or the victim of child abuse? Can a girl of 12 or 13 or 14 know what love and commitment are? And is marriage a better solution for everyone involved than a prison sentence? The public debate in Nebraska rages.

But for Bruning, Matt and Crystal are far from Shakespeare's star-crossed lovers. "I don't see them as Romeo and Juliet. This isn't about romance. This is about a grown man having sex with a little girl, a 12-year-old little girl."