@cromat On page 8, you can see the words "Time Enough for Love" on the side of the ship. This is a reference to a sci-fi novel by famous author Robert Heinlein, which is split into several smaller stories, all relating to incest. The joke is that incest is so common in manga but (relatively) rare in Western fiction, at least more recent stuff, so it's funny to see a manga mention a book by an American author that deals with incest when this Japanese story doesn't, rather than the other way around.
Also the plot is just that the dude was on a ship ten years ago which fell into the black hole but the captain helped everyone else escape while she got stuck inside it because time stops inside the hole. So now he snuck onto another ship to go back in and find her because he lovers her more than anything else in the universe. But because we don't see the part-timer until the last few pages and then someone talks about how this story of a lover going back into the black hole to be with his beloved for all eternity was from 100 years ago, it again suggests, as previous chapters have, that Motoka is somehow immortal because she was there serving that dude 100 years ago.