There are quite a few out there. 'The Golden Trio's Journeys' is a fanfiction that while not solely about 'lust', has some great relationship building among the characters. It delves into how they grow up and how their feelings for each other evolve. It's really interesting to see how the author weaves the story within the 'Harry Potter' universe. Also, 'Ginny's Perspective' gives a fresh view on the relationships within Hogwarts from Ginny's point of view.
Well, a lot of fanfiction explore different relationships in the 'Harry Potter' world. 'Ron and Hermione: A Different Path' is one that shows a unique take on their relationship. It doesn't go into improper 'lust' but rather shows the deep connection they could have. Another example is 'Harry's Hidden Feelings' which delves into the unspoken emotions of Harry towards his friends and how that could develop into something more meaningful.
One popular 'Harry Potter' fanfiction that has elements of romance (but not inappropriate lust) is 'Harmony's Song'. It focuses on the relationship between Harry and Hermione in a very sweet and well - written way. Another could be 'Luna's Love', which gives a different take on the wizarding world's relationships.