Don, a freelance photographer, is a descendant of a billionaire in Seoul. Don has lost his family. His father's last words for Don is to go back and pay homage to his grandparent's graves. Don was arriving in Thailand with a weary heart and damaged soul. He met Nilun an adopted child of the cafe owner. Nilun is working at the cafe, which has been passing down by generations. Besides, Nilun has been looking after and comforting Don. Arlex is Don's cousin and the son of Linda. He is another to comfort, cheer up and support Don. 

The relationship between Don and Nilun leads them to a romantic feeling which they never revealed. Until then, the day Nilun almost lost his beloved Cafe because of Linda and Don's fiancee Victoria. Nilun drops like a stone when he knows that Don is immediately arranged back to Seoul in order to get married to the fiancee of his family arrangement. 

How can Nilun and Don dealing with cold feet in their current romances? Will they set out to find each other again? Let's spell "Eternal" together in Nilundon, You're always in my heart soon.