India, June 24 -- A birthday surprise planned over a month. A flower-decked luxury convertible. A romantic dinner where he went down on one knee. And an emotional Instagram tribute after his death.

Those are among the chilling details emerging from the final weeks of Pune businessman Ketan Agarwal's life, after police arrested his fiancee, Siya Goyal, 20, and her alleged lover, Chetan Chaudhary, 22, for his murder.

Videos that have surfaced since the arrests show Ketan Agarwal, 25, organising an elaborate birthday celebration for Siya ahead of her 20th birthday on June 19. In one clip, he presents her with a bouquet inside a flower-decorated convertible. Another shows the couple at a restaurant, where Agarwal goes down on one knee befor...