Why Bristol Palin and Levi Johnston are back together

Which was more astonishing about Bristol Palin and Levi Johnston's big announcement on Wednesday:

# That the most famous teenage parents in America were engaged again, after a year of scorched-earth public bitterness?

# Or that Sarah Palin reportedly only learned about it from Us Weekly?

The twin developments launched a slew of conspiracy theories. (Was this for a reality show? Or the 2012 campaign?) But for all the murkiness about how the news came out -- and whether anyone was paid for it -- it may boil down to the fact that families are complicated, and so is love.

The high school sweethearts, who broke up a few months after the December 2008 birth of their son, Tripp, were interviewed by Us on Saturday in Anchorage, where Bristol Palin now lives. They said they bonded anew when they met three months ago to work out a custody plan.

"I really thought we were over," Johnston told the magazine. But feelings changed when they went for a walk with their son. Nothing romantic happened then, she told Us -- but later, he texted her saying that he missed her and wanted her back. "I was in shock," she says.

The 19-year-old mom said that her own mother -- who traded insults with her grandson's father in the national media over the past year, as he posed for Playgirl and dished dirt about the family -- didn't yet know they were planning a wedding: "It is intimidating and scary just to think about what her reaction is going to be."

Officially, Sarah and Todd Palin's reaction was restrained. In a statement, they noted their daughter is an adult: "We obviously want what is best for our children, but Bristol is ultimately in charge of determining what is best for her and her beautiful son. Bristol believes in redemption and forgiveness to a degree most of us struggle to put in practice."

Supporters of the former Alaska governor dismissed any notion that the reconciliation was engineered. "It will be highly cynical to look for a political motive in this situation which has brought two young people together," GOP fundraiser Fred Malek told our colleague Jason Horowitz.

Others doubt a marriage would affect her mother's political future anyway -- except, as University of Virginia politics professor Larry Sabato noted, to neutralize the Levi situation: "If they are together, then he won't reveal any information he has, if he has any." (A producer who was pitching a Levi reality series in March declined to comment about whether the project was still alive.)

But if Sarah Palin was truly left in the dark about this ... why? Melanie Bromley, the Us reporter who interviewed the couple, speculates that Bristol Palin wanted "to be in control" of the story. "I got the impression that Sarah had laid down the rules for Bristol -- that if she's back together with Levi, [Sarah] wants him to finish his education, and get a job. But she wants to be with Levi now."

By telling her story "in her own words," as Bromley put it, "she's forcing her mother to hear her side of the story without interruption."

Well, zing! Some other things about that story:

Bromley would not say whether the couple was paid for the interview (conducted at a private home rented for the occasion). A reporter from rival People magazine, Sandra Sobieraj Westfall, spent the following day with Bristol and Tripp in Anchorage, for a story in this week's issue. In her interview, which Westfall says was unpaid, Palin did not reveal that she was engaged -- and Johnston declined to participate. Rex Butler, Johnston's attorney, did not return our calls.

A final mystery: Why get back together? A better question might be: Who else could they date? They've shared a unique experience: small-town teens catapulted to fame by the unlikely convergence of an unplanned pregnancy and her mother's skyrocketing political ascendance.

Who else could relate to Bristol's life? Who else would ever really "get" Levi? This is why people fall in love.