Luke liked this. Listening to them, to their words and how they talked, and the feel of it. He was no natural reader, but being in the same room with them, he kept an 'ear' out, so to speak, and when they were like this, it felt good. These two women, one who was his wife, his other half, and his soul mate, for want of a better word, and one who was starting to feel almost like she could be a daughter, a person he cared about.
One of his few regrets from his previous life was that he and his wife had never found time to have a daughter as well as Ben, their son. It was not a fault of either, but simply the way of their times and that it had never been a priority. River felt much like he had thought a daughter could, and he wondered truly, at the way life worked, and the universes wandered. The Force always sent him where he was needed most, and this was his place now. He was glad of it too, as he listened, remembering his own mechanical works, and the ship he had built. That had been long ago, though, before Mara even. And he had been a very foolish young man then.
For now, he relished the sound of their voices, and that quiet happiness radiated from him, calm and peacefully. His smile, likely also gave away his joy.