Answer is simple......She just passed SLC (meaning that she is around 16 yrs of age...still immature)....he had grandchildren(around 40 years)...and probably the girl sawa lot of hindi movies with such storylines....and thought she was in love with the old-smart-guy...and might have thought that Jagjit Singh sang a Ghazal called "Naa umraki seema ho na janmka ho bandhan,jab pyaar kare koi to dekhe kewal mann" just for her... It happens at such age but its a good thing that it ended happily.....