Dr. Nicholson and the Blue Diamond (1913)

The premise is something along these lines. Through one of those quirks of law that I hope only occur in fiction, Alice Kensington, an heiress, is obliged to marry before she can claim her inheritance, which is to be substantial. She's an intelligent and independent sort, and decides to enter into a mock marriage (which is presumably a real marriage sans consummation) for one month, so as to gain her inheritance without being lumbered with a husband she doesn't want or love. She places an advert in the paper requesting a temporary husband, as you do.