Title. There's a sci-fi story I cannot for the life of me find, that starts on a spaceship with an older man, his son, his old flame, and his son's girlfriend (i dont think the two women are related, but am not 100% sure on that side). The son and older woman end up in an escape pod or going down to the planet surface or something like that, while the father and son's girlfriend are up on the main ship, and they end up swapping partners, and at the end there might be a scene where they hook up with their original partners again? I hope someone can help me find this! thanks