Consider the form of the sentence.
"I gave him enough love." Here, "enough" is an adjective describing the quantity of noun "love".
"What we gave him enough of is love." Here, the sentence is searching for something to describe "what". When we do this, the sentence takes on the following structure:
What + Subject + verb + "enough of' + object.
What he doesn't get enough of is exercise. He doesn't get enough exercise.
What do you have enough of, money? Do you have enough money?