After much searching, I am still finding (potentially) conflicting information regarding commas before subordinate conjunctions when they come at the end of the sentence.
Specifically, I have read that a comma before while indicates 'whereas.' No comma indicates time.
However, commas are also used before subordinate conjunctions when the subordinate clause is non-essential to the meaning of the sentence.
Therefore, I am confused whether to use a comma before while in the following sentence. Is there a rule you can refer me to?
"Stick to your guns, Lola," he replied happily, while pinching both of my cheeks.
Based on the above information, there should be no comma since the two actions are happening at the same time. However, the information also seems non-essential to the meaning of the sentence, which means that it would require a comma. Very confusing!