<P> When Karen becomes engaged to Keith, Brooke offers to design her wedding dress but, after Keith's death in the school shooting, Brooke attempts to help Lucas and Karen pick up the pieces of their lives . In the meantime, Brooke agrees to help Haley and Nathan in organizing their second wedding, becoming Haley's maid of honor and the designer of her wedding dress . However, when Peyton reveals to Brooke that she has feelings for Lucas, again, at Nathan and Haley's rehearsal dinner, Brooke becomes furious at her and promptly ends her friendship with a teary - eyed Peyton . At the actual wedding, things only become worse when Lucas, thinking Brooke already aware of the situation, accidentally lets it slip that Peyton kissed him during the school shooting . Clearly upset, Brooke and Lucas argue in private, with Brooke telling him that he never "let her all the way in ." </P> <P> As their love triangle begins to reassert itself, Brooke decides that she needs time to herself and breaks things off with Lucas, though she admits that she will always love him . With her friendship with Peyton now over, Brooke is invited to move in with Rachel . In the season finale, it is revealed that someone at Nathan and Haley's wedding is pregnant, with the evidence largely pointing toward Brooke . </P> <P> With the news of Brooke's "pregnancy" spreading around campus, the fourth season begins with pro-life advocates, calling themselves Clean Teens, pressuring Brooke to not terminate her pregnancy . However, it is soon revealed that Brooke has really been covering for her friend Haley . In an effort to get Brooke back into the dating pool, Rachel sets her up via an online dating site with a male model, Nick, under the guise of a female model named "Peyton ." The plan goes awry when it is revealed that Nick is also the new English teacher at Tree Hill High; however, the two continue their relationship in secret . When Rachel catches wind of the affair, she informs Brooke that Nick hit on her . As a result, Brooke confronts him, but he denies the whole thing and her friendship with Rachel becomes strained . Upon learning that Rachel was telling the truth and that Nick is cheating on her with one of her own models, Brooke dumps him and reconciles with Rachel . </P> <P> Around this time, Brooke realizes that she still is in love with Lucas; asking Lucas to be her date to the annual sports banquet, Brooke later tells him that it was a mistake and he heads home, with the two of them deciding to just remain friends . After Tree Hill's victory in the state championship, Brooke encourages Lucas to go with Peyton . When Brooke is failing her calculus course, Rachel pretends to need Haley's tutoring so that they can steal the answers to an upcoming calculus exam, but Haley refuses . Taking matters into their own hands, Brooke and Rachel break into the high school but are caught by Principal Turner; to serve as their alibi, the two join Clean Teens . </P>

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