Roberto Martinez resigned at full-time as Portugal again failed in their attempt to reach a first-ever World Cup final as Mikel Merino's late goal sealed Spain's passage.
Defeat to La Roja rounded off another poor showing for Portugal on the world stage, after draws against DR Congo and Colombia in the group stage, and just two wins from five in total.
Ronaldo was in tears at the end inside the Dallas Stadium and the 41-year-old admitted he now needs time to make a decision on whether or not to play on with the national team.
A new manager may look to go in an alternative direction, and Ronaldo's impact at the tournament has raised questions over his impact at the highest level, with just three goals scored in the USA .
Rooney - who was famously sent off at the 2006 World Cup after clashing with Ronaldo - had nothing but praise for him as a major call looms.
"He's dedicated his whole life to football, he absolutely loves it," Rooney told BBC Sport after the game.
"He's got a mentality which I've never seen before in any footballer. It goes beyond anyone else in terms of wanting to win every game, play in every game and score too.
"He doesn't hold back and he does believe that he's best player ever, which for some people he is."
Portugal are next in action in September at the start of the UEFA Nations League campaign where they face a double header against Wales and Norway.