I really love the detail you have gone for here. You have put a lot of technical thought into it, and it shows.
The way Gregory deals with things, keep on smiling, is really powerful. The uncertainty, the fear is so vast, they have put all their hope and faith in this one planet, and undergone this journey knowing they might find a planet that couldn’t support them. The element of not knowing exactly how long the oxygen will last, other than being slightly longer than is needed to get to Plasdiet combines with that to really build tension. I like that the ship doesn’t just contain experts, but genetic diversity has been considered. Also appreciate that the ‘lucky 9’ were indeed lucky, and not selected for representing their race at its ‘purest’. You do a great job of really giving the feeling of a generational seed ship (and damn, that is a great choice of art to go with this), especially with the references to the cultural developments they have experienced.
Life already existing on the planet they are seeking refugee on is a fantastic element, it really conveys the deserpation of those who commenced this journey, they could find a race more advanced than them, they might have travelled across space to die before they even touch the ground. There is so much they don’t know, all they can do is hope. It isn’t that Gregory isn’t scared, he knows the fear is too great, so instead of giving in to it, he keeps going. The touch on the idea of getting married, the way you phrase it, secondary to survival. They are in this together, and when they make it out, there will be time for that. For now, Gregory tries to keep smiling, and keep his head above the uncertainty that could easily overwhelm him.
Really enjoyed this <3