BACK BURNER
I came across the following sentence in a story titled Healing in Chicken Soup for the Grandma’s Soul.
Studies and boys and other high school commitments were relegated to the back burner.
My guess was that the heroine of the story paid less attention to her studies, boys and other high school commitments and more attention to her dying grandma. But the back burner stuff baffled me.
Some search results show that the expression originates from cooking. When cooking you would look after what is being done on the front burner while leaving alone the back burner. What is being cooked on the back burner does not need immediate attention. You might be making a stew on it. Therefore, it is deprioritised. If you put something on the back burner, you do not deal with it right now because there is something more urgent at hand.
Another example:
A fire broke out in the kitchen when Jenny was sewing. She rushed over to extinguish the fire and the sewing was put on the back burner.
Shengliver Studio 
In college, we still should put love on the back burner. every day is a miracle.