The Belgian striker, who is said to be in a contract dispute with the Toffees, took his Premier League tally for the season to 21 as the struggling Tigers were put to the sword at Goodison Park.
Speaking about the game, Koeman told BBC Sport: "It's great of course, you like to be confident at home. We have had a great run at home. But the final result didn't reflect what happened on the pitch.
"The fans love Rom and everyone loves Rom. Yes, you may be able to hold him back for 85 minutes but then he was focused to the last second. We killed the game perfectly.
"You need to have hope in life! Of course we like to keep best players and we will do the maximum to keep these players but the final decision will be with the player himself."