Actress Lindsay Lohan has been dumped by her on-off boyfriend CALUM BEST - because she's "too boring" when she's sober, according to British tabloid reports. The Mean Girls star ended a 45-day stay at Malibu, California's Promises Clinic on 13 July (07), having checked herself in May after being arrested on suspicion of driving under the influence, following a car crash in Hollywood. Since leaving rehab, the 21-year-old promised fans she will be leading a much quieter life, crediting her family and her romance with reality TV star Best for helping her stay out of trouble. But the couple's relationship seems to be at an end, after 26-year-old Best claimed the reformed Lohan was too "dull" for him to put up with. A source tells British newspaper the Daily Star, "Calum called Lindsay on Friday (20Jul07) and said that he was finding her post-rehab existence dull and that he didn't want to give up partying. "Calum loves Lindsay, but he's simply not in the same place as her anymore." The Hollywood star has recently been spotted voluntarily wearing an ankle bracelet which monitors the wearer's alcohol intake to prove her sobriety.