Between chapter 12 and chapter 13, the place to look is about halfway through chapter 13. This is the chapter that begins with Jonas being frustrated with the lack of choice that he has in the world. He's focused on not being able to choose what color to wear; however, he does make a connection to the larger concept. The Giver helps him understand that choice is a powerful and dangerous thing because people can make wrong choices.

Eventually, the chapter gets around to a point in which Jonas asks the Giver about why he doesn't have a spouse. Jonas even asks if the Giver is allowed to apply for one in the first place. The Giver explains that he is allowed to apply for a spouse, and he also explains that he has a spouse; however, she lives with the "Childless Adults." The Giver goes on to explain that having a spouse will be hard for every Giver because he/she will not be allowed to share much with the spouse. So much will have to be hidden from that person, including things like books. Thus, the life that Jonas is stepping into is likely to be a very isolated and lonely life.

"So there will be a whole part of your life which you won't be able to share with a family. It's hard, Jonas. It was hard for me."

The Giver tells Jonas something about his personal family life in Chapter 13.

What he tells Jonas is about the kind of issues that Jonas will face when he is the Receiver.  He tells Jonas that he will not be able to share his work with his spouse.  He will not be able to tell her anything about what happens in his days.  He will also not be able to tell her about the books. This is hard, he says.

He tells Jonas that he did have a spouse, but she now lives with the Childless Adults.