His actions weren't supported by everyone - including his own coach.
"Because of that, I've made coach (Mike) Tomlin look bad, and that is my fault and my fault only", Villanueva said.
Rooney noted that his team's players wanted to focus on playing football.
He said he's embarrassed.
The NFL has fined Pittsburgh Steelers players $1 million each for staying in their locker room during the national anthem.
Last season, then-San Francisco 49ers quarterback Colin Kaepernick refused to stand for the national anthem as a way to draw attention to police brutality against people of color and other rampant racial injustices occurring in America.
"When everyone sees an image of me by myself, everybody thinks the team and the Steelers are not behind me, and that's absolutely wrong", he said. "I made my team-mates look bad, and that is my fault and my fault only".
The Steelers held team-wide discussions prior to their game on Sunday with players trying to reach an agreement on how they would conduct themselves during the anthem.
"The players respect him and whatever he was going (to) do wasn't going to hurt the feelings of any of the other players on the team ... they all respect what he did for our country", Konick said.
Villanueva said his team would have joined him if they had known about the "extreme circumstances" he was going through before the game. Dozens of NFL players across the league opted to kneel during the national anthem after President Donald Trump said players should be fired by the NFL for kneeling. Villanueva told Heyward he was "shocked" by the pictures, Heyward said. "Unfortunately, I threw them under the bus unintentionally".