Heinlein left detailed notes and an outline for this novel, which he shelved and never finished (see http://www.variablestarbook.com/). Spider Robinson was nominated to finish Variable Star and the afterward in this book that explains his writing and creative process was interesting (for me, at least, but perhaps not so much for others).
It’s been years since I’ve read Heinlein, but Robinson did an excellent job in making this feel like a Heinlein book. Now that’s not necessarily a good thing for me, because I’m lukewarm on some of Heinlein’s books. However, Robinson wrote an enjoyable read. The premise is that the main character, Joel, gets picked to be a future spouse of a wealthy heiress named Jinny Conrad. Even though he thinks he loves her, he doesn’t want to buy into the straitjacketed life that’s planned for him, so he makes a break by getting onto a colony ship. Since time dilation means Jinny will be long dead by the time he’s starting to colonize the new planet, this break is a supreme definition of “permanent.” Granted, it’s an adolescent act and we get to see how Joel has to mature, both emotionally and intellectually. Things get worse for life aboard the colony ship, as well as mankind in general — but any more hints would ruin the story for you. Spider Robinson also provided possibilities for follow-on novels, which will be fine by me.