Ch1-4 is the main story; ch6 is an extra
The thing bugging me about the parents and the friend is idk if they're actually likeable. They're probably just supportive of the main characters because their memories and way of thinking are getting manipulated.
And... Well... How did the MC fall in love just because he remembered something from the past?
The story is as fast as the shooting star the alien was riding
Ch5 is a separate one-shot that's basically The Best Smell except it's a yaoi one shot
Uchuu De Ichiban Kimi Ga Suki