Posted:
I was looking at old episodes of geet when they went for honeymoon. I noticed that Dev was following Maan-Geet when they were in delhi(scene where geet gets a phone call at night, and when Maan takes geet for a movies and they show somebody watching them from the door).
I think he is just playing a good guy and his motive is to make Maan weak and take revenge. He wants to portray him as a bad guy infront of family and separate Maan and Geet. Thats why he wants to know everything about Geet from Maan and dadima.
Just my POV, may be I am thinking too much into it.