Doug Reinhardt isn't the only Hills hunk with a wedding in the works!

Lauren Conrad's ex-boyfriend Jason Wahler proposed to model Ashley Slack on Nov. 17, Us Weekly has confirmed; RumorFix was first to report the couple's betrothal. Slack shared the news -- and a picture of her stunning diamond ring -- with her Facebook friends. "I said yes! I am the happiest girl in the whole wide world and I cannot wait to spend the rest of my life with my best friend."

Wahler also shared a picture of his bride-to-be's ring on Instagram. "Love you babe," he wrote in the caption. The couple will tie the knot on Oct. 12, 2013. (Reinhardt, who also romanced Conrad, announced his engagement to high school sweetheart Allie Lutz via Instagram Jan. 6.)

Three months before his proposal, Wahler spoke to Us about how he knew Slack was The One. "I found someone I really genuinely care about as a friend," the Laguna Beach star said. "My parents have been together 40 years, they just celebrated that. They're best friends deep down. That's kind of what you have to find."

The couple met through "mutual friends," Wahler explained. Their first dinner date was "probably one of the best times I ever had," he added. "It was just so natural and organic. We just hit it off! It was pretty meant to be!"

Following six alcohol-related arrests, Wahler -- who dated Conrad from 2005 to 2006 -- cleaned up his act on VH1's Celebrity Rehab in 2010. "This is the first relationship I've ever been in sober," he said of dating Slack. "It's a little bit different when you're not drinking and going out. She's my best friend."

Wahler imagines they will start a family "within the next five to seven years."

"Things are going good," he assured Us. "You just have to take them when they come."

This article originally appeared on Usmagazine.com: Jason Wahler Is Engaged to Ashley Slack -- See Her Ring!