Mary Robinette Kowal has nice range as an author. She can do an effective hard SF story, and also does well in fantasy. The Lady Astronaut of Mars falls on the hard SF side, but it is really more of a human relations story.
We have an alternate history element--in this history Washington, D.C. was obliterated by a meteorite strike early in the space age (insert politician doom joke here). Earth was thus energized to pursue space travel in self defense, trying to start colonies elsewhere in order to ensure continuity of the race. We thus went to Mars with technology similar to that which took us to the Moon.
Our protagonist is one of the first (and very few) female astronauts. She has both taken advantage of this, and been held back by it. But she was one of the most popular figures in the space program. She is now 63, and her husband, who did (and sometimes still does) programming for the space program is in very poor health. They live on Mars.
She is offered the opportunity to travel to a nearby star with an inhabitable planet. Near light speed, but she will still be gone three years. Her husband will die soon. Should she go, or not? That's the frame in which the emotions play out.
It's a good story, and worth the time to read. 3 stars from me.