Maybe the hero is a writer himself. And while exploring different works, he falls in love with another novel. This could inspire him to write in a new style, or it might make him feel a sense of envy towards the author of that novel. He could also try to find ways to incorporate the elements he loves from that novel into his own writing.
In many such novels, there is often a brave prince as the hero. For example, Prince Alexander in 'The Royal Love Affair' who falls in love with a commoner girl. He is a popular character as he has to fight against the norms of the kingdom to be with the one he loves.
One way to interpret it is that the hero sees the other novel as a form of escape. He might be in a difficult situation in his own story, and the novel he loves provides a mental refuge. It could also represent his taste in literature, which in turn can be used by the author to show his character's sophistication or naivete depending on the nature of the novel he loves.
You might consider 'Wuthering Heights'. Heathcliff's love for Catherine is intense, but he also has an entanglement with Isabella. It's a classic with lots of drama and passion.
There could be many heroes in different stories who might love other novels. It's not specific enough to name just one. It could be a hero from a coming - of - age story who finds solace in the pages of other novels.
The special part could be the unique way they meet and the challenges they overcome together. Maybe it's the depth of their emotions or the unexpected plot twists.
One popular one is 'Sword Art Online'. Although it's mainly about being trapped in a virtual world, the main character Kirito can be seen as a hero in that new world. He has to fight various challenges and enemies to survive and save others. Another is 'Overlord'. The protagonist Momonga is transported to a different world where he is an all - powerful being and has to navigate this new realm with his loyal minions.