Looks like Lindsay Lohan has grown tired of living the life of Riley. The employment-challenged, short-attention-span starlet, 21, is reportedly flying solo after giving sometime snowboarder and constant post-rehab companion Riley Giles the heave-ho.

"They're over -- they've broken up," an insider declares to People. "They split after Thanksgiving weekend."

So what went wrong with the 12-step-climbing couple, whose romance began oh-so-auspiciously a few months back after they met at Utah's Cirque Lodge while battling their respective DUI-tinged demons?

"Lindsay gets bored easily, and she just reached a point when she wasn't interested in dealing with him anymore," an insider tattles to the New York Daily News. "Riley was really unpopular among [her] friends and family. No one really cared for him, and Lindsay eventually started to see it."

Echoes a mole to E! Online, "They thought he was unsophisticated and told her she should have left him in Utah with his snowboard."

But a "lifelong friend" of Giles insists to the Chicago Sun-Times that he, too, was gripped with doubt over the relationship.

''Riley was also having second thoughts about the whole thing," says the source. "He knows that people in the early stages of recovery should avoid romantic entanglements -- with both recovering addicts and with other people as well."

The Giles mole also tries the "I know you are but what am I?" defense, telling the paper, "On top of all that, Riley realized Lindsay isn't the girl for him in the long term -- plus he found her family and friends in New York a real turnoff.''

The depressingly predictable parting of ways apparently came a short time after a disastrous Thanksgiving holiday spent visiting Lohan's dysfunction-filled, Long Island-based family.

"Riley partied all week in NYC without Lindsay, when she asked him to stay in with her or go out and do things with her friends," the spy adds to the News, which just placed LiLo at the top of its list of the "Top 50 Dumbest People in Hollywood," citing "poor movie choices, delinquent behavior and bad taste in men." "The whole point of him joining her was to hang out in her hometown as a couple. Not to party all night long without her."

E! Online says Giles, who has denied claims he ditched his longtime love (and rumored cubic zirconia-receiving fiancée) to take up with Lohan, received his walking papers when they returned to Los Angeles early last week.

"She made it pretty clear when they got home," shares a snitch. "It's over."

Among the problems purportedly plaguing the issues-crammed duo: sulkiness, stinginess and wounded pride.

"It was fine when they were in Utah, just the two of them," explains the source. "But then they returned to L.A. and Lindsay was shooting a movie, photographers followed them everyone, she had meetings with this agent, that publicist, this director. His ego couldn't take it."

What's more, "She got tired of him pouting all the time," continues the confidante, griping for good measure, "He never paid. Yeah, we know Lindsay is the rich and famous one, but come on. Be the man once in a while! Pay for a round of Cokes. I mean, they weren't even drinking alcohol, so how much could a round of Cokes be?"

LiLo doesn't seem too broken up over the split. In the last few days, paparazzi have twice caught her in proximity to Stavros "I Dated Paris Hilton and All I Got Was This Lousy Reputation" Niarchos, whom she was linked to for about a nanosecond last year.

Declares the source to People, "She is concentrating on her life and her career."

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