It's hard to say. You might need to do some research or look for reviews and comments from people who are familiar with it to find out if it's based on a novel.
I'm not sure exactly what the ending of 'ishq mein marjawan' is as I haven't watched it fully. But generally, in such shows, it could end with the main couple getting married and living happily ever after. Maybe they overcome all the obstacles like family differences or some villain's plots.
I'm not entirely sure as I haven't read 'aatish e ishq novel'. But often novels with 'ishq' (which means love in some languages) in the title might have love as a main theme. It could be about different forms of love like passionate love, unrequited love, or love in the face of difficulties.
Love is likely a main theme. The 'ishq' in the title often refers to love in Urdu literature. Another theme could be the wandering or 'awara' nature, which might represent a character's journey in search of something, perhaps love or self - discovery.
I'm sorry, I don't have the specific 'ek boond ishq' full written story at hand. It could be a story about a single drop of love, perhaps exploring themes of love's origin, its growth from a small beginning, or a love that is as precious as a single drop in a vast world.