Supporters were delighted that a player developed by the club had made such a big impact in a Premier League fixture.
"They love Rom", Koeman told Sky Sports. Lukaku is the first Everton player to score 21 league goals in a season since Gary Lineker in 1985-1986.
The Toffees had been confident the Belgium global would sign a new five-year deal thought to be worth around £140,000 a week.
Koeman, speaking in an interview via Mirror, has since pleaded with the club's avid and passionate supporters to brush the obscurity surrounding Lukaku's future aside, and get behind the 23-year-old as he aims to fire the Toffees and himself towards European football.
Lukaku surprised Everton this week by announcing he wouldn't be signed a new deal, though his current contract doesn't run out until 2019, and it is understood that talks remain ongoing and Everton still believe that he could sign an extension to his deal.
Valencia returned the favour, with a through-ball for Lukaku in the first minute of stoppage time.
Eruptions continue at Etna after explosion that injured ten
A volcano erupting must be one hell of a sight, but most of us would prefer to watch it from a safe distance. One volcanologist told Ms Morelle the explosion was the most most unsafe he had seen in his 30-year career.
Hull manager Marco Silva, who is still looking for his first away win since taking over in early January, was unhappy with the red card, which killed their momentum, but will wait to see replays of the incident before deciding whether to appeal.
"We need the support, every player who is starting needs support".
"Of course we like to keep best players and we will do the maximum to keep these players". However, it looked to be a harsh decision from the replay.
Meanwhile, Everton midfielder Morgan Schneiderlin is facing "several weeks" out after suffering a calf injury against Hull.
Their first game back after the global break is away to Liverpool in the Merseyside derby on Saturday, 1 April (12:30 BST).