Movies/tv shows in which couples look unintentionally better paired with other characters

Which movies or tv shows do you think best correlates this thread?  As an example of my own, I always kind of thought the Harry Potter movies were on to something more with Harry and Hermione as a pairing, as cliche as they may have been.  They definitely had the chemistry of a dream couple compared to their actual relationships, and the movies even picked up on their potential whether the books already called for it or not(I don't know).

What are some examples you have for this thread folks?