There is 'Anna Karenina'. Anna's love for Vronsky is complex and in some ways unrequited as she sacrifices so much for him, but their relationship is fraught with problems. Vronsky doesn't always understand or meet her emotional needs. Another example might be some works of Thomas Hardy, like 'Tess of the d'Urbervilles' where Tess has unrequited love in a cruel world that doesn't allow her feelings to be fully realized.
A 'echoes unrequited love novel' like 'Wuthering Heights' is a great example. Heathcliff loves Catherine deeply, but their relationship is full of misunderstandings and the inability to fully be together. His love is unrequited in that it doesn't lead to a harmonious, happy relationship. Also, 'Pride and Prejudice' initially shows Elizabeth having some unrequited feelings towards Mr. Wickham before she realizes his true nature.