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Someone walks by and says, "Why don't you play that song?"
"I'd like to. But someone has to come and sit down here and play it with me."
"Well, you're just not trying hard enough." And she walks away.
Then someone else walks by and asks, "How come you don't you play that song?"
"I'd like to. I'd love to play this song - I'm sure the music's beautiful. But someone else by their own agency has to to be willing to sit here and play it with me."
"Well, you could play it if you had more faith." And he walks off.
Yet again, another person walks by and says, "Why don't you play that song?"
"I'd LIKE to. I love the music. I'm sure it's a beautiful song. But someone with their own agency that God will not violate has to choose to sit here next to me and play it with me."
"Oh, you're just being too picky." And he walks away. Anyway, his point was that marriage isn't something that can be forced. But I'd like to talk about what he said next.
He said not to get discouraged about these people who keep asking you about being single, because these individuals with an underdeveloped sense of appropriateness never go away. These are the same people who, once you get married, ask, "So when are you going to have kids?" And then once you have kids, ask, "So when are you going to have more?" And then, "So when are you going to go on a mission?" They NEVER go away. So keep smiling and don't get discouraged.
I am of the (rather strong) opinion that a couples' decision to have children, and when they decide to have them, is their own business. It is between them and the Lord, and no one else. Not their bishop, not their parents, not their friends, and certainly no one in their ward who barely knows them. I had a friend who, when pressured by her father to have children, would say, "We're trying all the time, Dad!" That would usually shut him up.
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But even for those people who, by choice, are not currently trying to have children, is that any of your business? Now, I'm not trying to say anything about me or my wife with this post. We've only been married 5 months, and haven't received a ton of comments about our childless state. And as a disclaimer, there are plenty of polite and tactful ways to ask about a couples' plans for having children, which leave the couple the option of not answering if they don't want to (i.e. "Have you guys thought about kids yet?"). But if you want to avoid any awkward moments, I'd recommend not even trying. They'll talk about it when they're good and ready.
And my favorite response to a single person asking about our plans for children? "When are you gonna get married?"