-they both respected the institution of marriage,
-soon fell in love genuinely,
-accepted each other emotionally, mentally and physically,
-live for each other...
Prachi is only faking her marriage to Proteek in a compromise (as she left Milind to save him) and Milind is roaming directionless searching for her.
There is no question of someone else in Milind's or Prachi's life. They are still husband and wife, separated physically now, but their hearts still beat for each other and their souls long for each other.