Venetia met Asquith through her close friendship with his daughter, Violet. Asquith, who enjoyed writing letters to women in high society, began his correspondence with Venetia in 1910.
However, Venetia was just one of several women who received Asquith's letters until 1912, when she went on a trip to Sicily with Asquith, Violet and Edwin Samuel Montagu, a Liberal MP who was one of Asquith's protégés. It seems that on this trip, both Asquith and Montagu fell in love with Venetia.
His romantic obsession with her continued into 1915, when she married Edwin Montagu, a Liberal Cabinet Minister. A volume of Asquith's letters to Venetia, often written during Cabinet meetings and describing political business in some detail, has been published; but it is not known whether or not their relationship was sexually consummated.
Recent evidence suggests that a Louis T. Stanley, born in 1912, was the illegitimate son of this relationship. At the same time, Montagu was attempting to court Venetia and unsuccessfully proposed marriage to her in 1913. Venetia liked Montagu but did not reciprocate his love.
Asquith's epistolary obsession with Venetia (by early 1915, he was writing her up to three letters a day) was not just an emotional dependence.Although Venetia was intelligent, well-read and keenly interested in politics, she apparently felt overwhelmed by Asquith's demands. As a result, she finally accepted Montagu's proposal on 28 April 1915 and wrote to Asquith of her decision on 12 May.
Within days of his rejection by Venetia, Asquith started an intense relationship with her older sister Sylvia, which lasted for several years.