Why does Jonas see love in a family as dangerous?

Ever since Jonas's society adopted the Sameness, they have been ruled by logic.  That should make sense since a result of the Sameness was a general elimination of emotions.  Put simply, Jonas's society saw emotions as a big enough problem that they got rid of them.  Now, the society makes all decisions based on cold logic, and it is seen as smart and safe.  The people believe that emotions could cloud a person's judgement, and...

Ever since Jonas's society adopted the Sameness, they have been ruled by logic.  That should make sense since a result of the Sameness was a general elimination of emotions.  Put simply, Jonas's society saw emotions as a big enough problem that they got rid of them.  Now, the society makes all decisions based on cold logic, and it is seen as smart and safe.  The people believe that emotions could cloud a person's judgement, and that is what Jonas says in chapter 16 about love in a family.  

The Giver is showing Jonas a memory of Christmastime and family love.  On the whole, Jonas likes the memory and the feeling of love.  He even admits that the family felt more "complete" because of the emotion. 

"I liked the feeling of love," he confessed . . . "I wish we still had that," he whispered.  

This entire sequence is a great sequence because the reader can see the logical centers and emotional centers of Jonas warring with each other.  He knows that he liked the feeling of love, but he also knows that he should not want to have that emotion.  He has been told his entire life that emotions are dangerous, and that is what he tries to do here too.  Jonas comes up with two reasons why love is dangerous and bad for a family.  

The first reason is that the elderly grandparents would be present at the celebration.  This would be bad because they would not be getting the great and proper care that they get now. 

"It wasn't a very practical way to live, with the Old right there in the same place, where maybe they wouldn't be well taken care of, the way they are now."

The second reason that Jonas believes love could be dangerous is because it caused them to have candles burning and a fire in the fireplace.  Jonas believes that was a risky thing to do all for the sake of a warm and loving environment. 

"Well," he said finally, grasping for an explanation, "they had fire right there in that room.  There was a fire burning in the fireplace. And there were candles on a table. I can certainly see why those things were outlawed."