This is so well done, the awkward expressions on lumine as if she just ask for politeness and not because she thought he would say yes and then as she slowly just gets in the mood and stops caring anymore and just reciprocates 11/10.
Only thing i'm iffy about is that ending, seemed like a pretty abrupt mood shift from all that intimate lovey dovey sex to Lumine suddenly giving Aether the cold shoulder, bit of a mood killer to be honest. Think the animation just fading to black after the creampie would be a better ending.