Hoshi no Koe, Pale Cocoon Recommendations
Both Mikako of Voices and the protagonists of Pale Cocoon are forcibly alienated from Earth. Both stories take place in a depopulated and dystopic future, and emphasize a kind of ethereal nostalgia for the "Home Planet." Both involve elements of ambiguous romance.
Both OVA takes place in the distant future that tells a tale of humanity and the truth of society.
Both series has a nice soundtrack that is appealing to the ears.
Both series has that melancholy feeling that seems to reflect emotions and sadness. Additionally, they also have science fiction themes that details humanity's future; a scientific touch in the anime world.
Both are calm and quiet scifi anime in which the character's careers bring them farther apart from each other.
Both deal with the relationship of 2 people in the context of humanity being in danger, in the future.
Both of these anime are short 25 minute movies about loneliness in a science fiction setting. Both of these anime spend most of their time illustrating this loneliness and both end without full resolution of the issues brought up.