As the series progressed, Montag began dating fellow cast member Spencer Pratt, which ultimately ended her friendship with Conrad.
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Heidi Blair Pratt née Montag; born September 15, 1986 is an American television personality, singer, fashion designer, and author.
Their ensuing feud became the central focus of the series, and was carried through each subsequent season.
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Born and raised in Crested Butte, Colorado, United States of America, she befriended Lauren Conrad in 2005.