The few years I lived in PR I found most everyone with whom I had contact were pro-American. However, there were a large number who were not. The “independistas” were only 1% of the population, but many were sympathizers and who went out of their way to make resident Americans feel uncomfortable. We had many military installations on the island with Roosevelt Roads Navy base being the largest. Millions of American dollars flowed into the island from the military and civilians on a US payroll - government or business. Over the years the Puerto Rican government and media made it easy for the US to pull out of the island.
The economy had always been weak, but without US dollars to prop it up it became much worse. The Puerto Ricans are the reason for their lousy economic condition, not the Americans and their money. P.S. - we loved living on the island.
I was stationed in PR in the early 60’s. Had a great time, by the way in Old San Juan! But there were serious terrorist factions that bombed military school buses carrying military dependents. Very anti-American groups.