One cannot forget that show business also deals with humans. Everything is not so superficial that this is rigged or planned. Sometimes people do fall in love with each other because they spend a lot of time on the sets so much so the set becomes your first home, and your actual home becomes your second home.
I signed 'Iss Pyaar Ko Kya Naam Doon' only for a year. But the producer requested me to stay on, as the show had just started to make money. I carried on, and in the process, the character became very popular. When I finally gave up, changing the actor for that character was difficult, so the show ended.