Jessica Simpson just can't get over her break-up blues. And the fact that her ex, Nick Lachey has been spotted cozying up to yet another woman can't be helping things. According to sources for Star magazine, instead of letting go and moving on, Jessica can’t stop thinking about Nick. Her regrets over their split just keep getting bigger.

A source explained Jessica's feelings to Star: "Things haven't exactly been idyllic for Jess. And now she has just enough distance from Nick to see all the good things about their relationship. She's definitely feeling regret about her decision to leave him - and she thinks maybe she threw in the towel too fast." Especially since, while she's in the doldrums, Nick's been busy moving on!

According to the source, Simpson has finally come to terms with the fact that fame may have ruined her marriage. "Jessica realizes she and Nick never really had a chance to make it work, since they lived under a microscope, with camera crews breathing down their necks. There wasn't private time for them to work out problems," the insider said.

What kept the relationship from working out may have been the fact that Simpson married so young. "Jessica was a different person then," the source said. And Simpson's youth and immaturity caused her to seek out other men. But now that’s she's more grown up,"Jessica's learning that most men aren't as interested in commitment as Nick was," claims the insider. "The fling with Adam [Levine of Maroon 5] left her feeling empty. That relationship was based on nothing more than intense physical attraction."