A Mother's famous words that all children hate to hear. Not really a reason when she says, "No."
As a child of God, we all have a handbook called the Bible, that gives us our guidelines on how to live our lives. There are times when God tells us, "No" with no real rhyme or reason to it all, at least, that we can see. When we ask Him to tell us why, He just says, "Because I Said So..."