Star magazine reports that Hilary Duff is frustrating boyfriend Joel Madden by refusing to let the Good Charlotte singer past first base. “They kiss, but that’s as far as Hilary will go,” a source told the tab. 17-year-old Duff, who becomes “legal” next week (September 28), has a midnight curfew and is under the watchful eye of her mother Susan. “Her mom trusts her and feels that when Hilary wants to take that plunge, she’ll talk to her first,” the source added. How is Madden handling the situation? “He’s not the kind of guy to put pressure on a girl, but it’s tough,” the source said.