In the buildup to the showdown, there were suggestions that Masters champion Willett would receive personal verbal attacks from fans after his brother Peter Willett described them as a "baying mob of imbeciles" and "fat, stupid, greedy, classless bastards" in a column for National Club Golfer.
Willett, who failed to win a point during the tournament, apologised for his sibling's remarks before the first tee off, but appeared to defend the comments after Sunday's defeat.
The 28-year-old tweeted: "Very strange week here at the Ryder cup.. Tried my best but played poorly.. Unfortunately some american fans showed that @P_J_Willett was.... In fact correct.. Nothing to blame my bad play on.. But still shows that sometimes fans don't know when to call it a day.. Shame really!!"
The USA's victory was their first in eight years.