Paheli

Paheli (The Riddle) is a 2005 Hindi language movie directed by Amol Palikar and produced by Gauri Khan. It stars Shah Rukh Khan and Rani Mukherji.

A ghost living by a tree in the dessert sees the nuptial parade of the beautiful Lachchi (Mukherji) and falls in love with her. Lachchi is being sent to be married with Kishanlal (SRK), the very dutiful son of a rich merchant. Unfortunately, Kishan is sent by his father to a long business travel the very next day after their wedding, not even letting the just married have their wedding night. The ghost, learning of this, immediately adopts the shape and voice of Kishan and goes to her new home to seduce her by pretending to be her husband. While the courting goes better than expected, the ghost gets an attack of conscience and ends confessing the ruse to Lachchi before they get too far, so she can choice what she wants.

Lachchi finds herself in a riddle: stay loyal to the husband that left her, o embrace this individual with the voice and face of her husband but that is also more loving, social, and confident than him. She decides to take the ghost as her husband. The ghost then ingratiates with Kishan's family, and the couple have a few years of familial blessing. Unfortunately, Lachchi gets pregnant, and the rumors get to the real Kishanlal, who immediately gets back to his home only to find a doppelganger living with his wife and family. Now the riddle for the family has become who is the "true" Kishanlal here...

Tropes used in Paheli include:

Because You Were Nice to Me: Lachchi prefers the ghost to her legitimate husband, as the ghost treated her with more love, passion, and consideration than the man she was married to.
Color-Coded for Your Convenience: When the ghost takes the form of Kishan, he wears more colorful clothes than the man he's mimicking.
Distracted by the Luxury: The ghost keep Kishan's father of asking too much questions by giving him gold coins.
Doppelganger: the ghost and Kishan.
Framing Device: apparently the story is being told in a puppet theater, and there are marionettes introducing and giving the conclusions of the tale.
Mama's Baby, Papa's Maybe: The ruse is only discovered because Lachchi gets pregnant, and people went to congratulate Kishan... who hasn't seen his wife since their wedding some years ago.
Our Ghosts Are Different: the ghost in this story can shapeshift, take physical form, create gold from nowhere, impregnate a living being, and, in the end, posses a human indefinitely.
Shapeshifting Lover/Shapeshifting Seducer: The ghost can take several forms (we see him transfom in, among several animals, a mouse and a bird), before taking human shape. He adopts the appearance of her target's husband to be with her.
Wisdom from the Gutter: when bringing Kishanlal and the ghost to the king to help them to guess who is the real and who is the doppelganger, the relatives of Kishan get helped by an ordinary goat herder.