After two and a half years together, The Hills star Lo Bosworth and Scott Hochstadt have called it quits, a source tells UsMagazine.com.
The sad split went down on Tuesday night, right before businessman Hochstadt, 33, attended a launch party for the Family Guy "It's a Trap" DVD at L.A.'s Supper Club; Hochstadt took his parents, not 24-year-old Bosworth, to the bash.
The duo first stepped out together in summer 2009; on July's series finale of The Hills, Bosworth agreed to move in with her man, who hinted at a future proposal. And the reality star gushed to Us that same month, "I think he is The One," and that she wanted to be a "young bride."
What went wrong?
"They had talked about getting engaged quite a bit," the source concedes. "But over the last couple of weeks it really unraveled...The age difference was a lot, and they are at different places in their lives."
For now, adds the source, "They are taking it slow as friends. Scott loves her family, she loves his family, and all their friends are heartbroken but they couldn't make it work anymore."

It’s time for some Rumor Control! In today’s edition, we heard a rumor that The Hills star Lo Bosworth is engaged! Hollyscoop has the truth.
It couldn’t be father from the truth! Bosworth’s rep tells us, “She is not engaged.”
So where’d this rumor come from? Star magazine. The tabloid claims Lo is engaged to her lacrosse player boyfriend Scott Hochstadt.
A source told the mag, “Lo was absolutely glowing. She’s having a hard time staying quiet about it.”
While Lo and Scott are dating and now living together, they have not taken that next step in their relationship. Plus, with the launch of Lo’s brand new website TheLoDown.com, she probably has zero time to be planning a wedding.
Lo’s only 23—she has plenty of time to get engaged.

French Connection Celebrates it's Fall 2010 Collection at Soho House in Los Angeles. Lo is photographed with Jamie-Lynn Sigler, Amber Lancaster, Noureen DeWulf and boyfriend Scott Hochstadt.

Lo and Scott attend Power Balance Goes "All-In For A Cure" at Drai's Hollywood on August 3, 2010 in Hollywood, California.

Wedding bells for The Hills' Lo Bosworth and Scott Hochstadt?
Could be!
On Tuesday's series finale of MTV's hit, Bosworth's lacrosse player beau hinted at a proposal in the future -- and she agreed to move in with him.
"I think he is The One," Bosworth, 23, told UsMagazine.com of Hochstadt at Wednesday's Lia Sophia Summer Party in West Hollywood. The pair first stepped out together last summer.
Of an engagement, she said, "we are sort of heading in that direction...[but] not in the next six months," she said of becoming husband and wife. But, she hinted, "I would like to be a young bride."
As for living together, she explained, "we are transitioning slowly but surely."
Bosworth, who just launched her lifestyle website thelowdown.com and has a book due next January, gushed of the impending cohabitation: "I'm just excited! He's the guy so I can't really be happier than that."