Ashlee Simpson & Pete Wentz's Post-Split Lunch

Ashlee Simpson and Pete Wentz are in the process of ending their marriage, but the former couple seem to be proving that their split is indeed amicable.

"They had lunch together today with Bronx at the Beverly Hills Hotel," a source told PEOPLE Monday, adding that Simpson is still staying at her parents' home in Encino, Calif.

Another source says the couple are not reconciling, but that their breakup remains friendly and being good parents to 2-year-old Bronx is their priority.

"They just had a meal together with their son," the source tells PEOPLE. "They're both focused on making this transition as easy as possible for him."

The couple – who pals say split because they wed too young, didn't have enough time to spend together and simply grew apart – announced last week that they were going separate ways.

Wentz, 31, and Simpson, 26, wed in 2008.

Credit: By Dahvi Shira and Pernilla Cedenheim for PEOPLE

Ashlee and Pete's Split: Early Signs of Trouble

Wedded bliss didn't last very long for Ashlee Simpson-Wentz and Pete Wentz.

Although the couple's Wednesday divorce announcement came as a shock to many, insiders saw trouble brewing way back in June 2009 -- when Ashlee, 26, and Pete, 31, were married for a mere 13 months, and prone to explosive blowouts often punctuated by alcohol.

At issue? Balancing their professional and romantic lives with the pressures of parenting an infant son, Bronx, then 7 months.

At the time, the duo fought "constantly," and singer-actress Ashlee was "seriously considering leaving him," one insider said.

Things boiled over at a June 1 party -- where a visibly drunk Ashlee got into a nasty public spat with Michelle Trachtenberg, Pete's ex girlfriend.

Simpson-Wentz was "reverting to drinking and going out, because she is sick and tired of her life," another pal said. The alcohol was "an outlet for her unhappiness, and Pete is getting fed up."

After hanging out in the same social circles for years, the couple got romantic in late 2006 -- and raced to the altar in May 2008, when she was 3-months pregnant.

"Ashlee loves Bronx but jumped into marriage and having a baby too quickly," one pal told Us. "They feel they got trapped in a situation they were too young for."

In Wednesday's statement released by their spokesperson, the couple said: "We remain friends and deeply committed and loving parents to our son Bronx, whose happiness and well-being remains our number one priority."

Credit: Us Magazine

Ashlee Simpson-Wentz Files for Divorce

The 2½-year marriage of Ashlee Simpson-Wentz and Pete Wentz is over, Ashlee's rep confirms to PEOPLE.

"After careful consideration, we have made the difficult decision to file for divorce," the couple said through a spokesperson. "We remain friends and deeply committed and loving parents to our son Bronx, whose happiness and well-being remains our No. 1 priority. We ask that everyone honor our privacy as we navigate this next phase of our lives."

According to TMZ, the divorce documents were filed in L.A. Superior Court, with Simpson, 26, citing "irreconcilable differences" and seeking spousal support.

In the court papers, which were signed by Simpson-Wentz on Monday and filed on Tuesday, it says the couple's date of separation is to be determined. Simpson-Wentz is seeking primary physical custody of their 2-year-old son, Bronx, with visitation for Wentz. She is also seeking to go back to her maiden name of Simpson and drop "Wentz."

Credit: Stephen M. Silverman for PEOPLE

Ashlee Simpson & Pete Wentz Leaving Beso

Pete Wentz and Ashlee Simpson leave in good spirits after enjoying dinner at Beso in Hollywood last night, December 15, 2010.

Credit: Zimbio

Photos by PacificCoastNews.com

Ashlee Simpson's Awkward Family Xmas Photo

Ashlee Simpson and Pete Wentz broke out the ugly Christmas sweater, swept their hair back into the mullet of yore and shook their holiday printed pijama pants down to Third Street Promenade in Santa Monica, CA today (December 11).

Joined by their son Bronx Mowgli, the former celeb couple was all smiles as they pose for a family portrait onboard the Old Navy Awkward Holiday Photo Mobile.

Credit: Faded Youth Blog

Ashlee Simpson & Family Shop At Whole Foods

Ashlee Simpson, Pete Wentz and their son Bronx went grocery shopping at Whole Foods in Sherman Oaks today, November 24, 2010. The couple got into the holiday spirit and bought a poinsetta.

Credit: Zimbio

Photos by Photo Agency

Ashlee Simpson: Shopping With The Family

Ashlee Simpson-Wentz, Pete Wentz and their son Bronx out shopping at Tough Cookies Children's Boutique in Sherman Oaks, CA. Ashlee was showing off her new short hair-do.

Credit: Zimbio

Photos by Photo Agency

Ash Simpson & Pete Wentz: 'Runaway' Premiere

Looking for a little Monday night action, Ashlee Simpson and Pete Wentz were spotted at the premiere of Kanye West’s short film “Runaway” in Los Angeles.

The “Pieces of Me” songstress and her “Sugar We’re Going Down” rocker hubby both looked to be in good moods as they arrived at The Harmony Theatre on Sunset Boulevard.

Credit: Celebrity Gossip

Ashlee, Pete & Bronx: Sherman Oaks Playdate

Bringing an end to the weekend with a family excursion, Ashlee Simpson and Pete Wentz took Bronx Mowgli out to a local park in Sherman Oaks, CA on Sunday (September 26).

The "Melrose Place" cutie and her Fall Out Boy hubby eased their way to the kiddie's paradise as they watched on while their young son played in the sand in between utilizing the swingset and slides.

Credit: Celebrity Gossip

Jessica Simpson Debuts Denim Collection

She’s always up to something, and last night (September 7) Jessica Simpson was spotted showing off the Spring 2011 Jessica Simpson “Show Me Your Blues” Jeanswear collection in New York City.

Joined by her sister Ashlee and brother-in-law Pete Wentz, the “Come On Over” songstress was all smiles as she posed at the launch event and press preview.

Credit: Celebrity Gossip

Ashlee Simpson & Pete Wentz: US Open Couple

Ashlee Simpson and husband Pete Wentz really enjoying the action and the bar at the US Open! Ashlee was particularly animated, even showing off her high kick moves at one stage, as she watched Roger Federer defeat Austria's Jurgen Melzer in straight sets in the Arthur Ashe Stadium at Flushing Meadows.

Credit: Zimbio

Photos by PacificCoastNews.com