The Belgian superstar was competitive throughout the brutal 254km of racing through Belgium, but eventually fell victim to a huge attack from Mathieu van der Poel on the Oude Kwaremont.
Despite putting in a spirited chase, Jumbo-Visma rider Van Aert eventually dropped back to join a chasing group, sprinting to a top-10 finish.
Speaking to Dutch broadcaster Sporza after the race, the 26-year-old said: “The second time around Kwaremont I already felt that I had no surplus.
“I just wasn’t good enough in the end. I continued to fight, but I was finished in the final.”
The decisive moment in the 2021 Tour of Flanders came when Kasper Asgreen (Deceuninck – Quick-Step) attacked the leading group 26km from the finish and was followed by Van der Poel (Alpecin-Fenix) and Van Aert.
That trio extended their advantage over the chasers behind, when Van der Poel put in a huge attack on the final ascent of the Oude Kwaremont, which left Van Aert trailing as Asgreen was able to follow.
The race came down to a two-rider sprint between Van der Poel and Asgreen, with the latter taking a surprise victory as Van der Poel’s legs gave way at the line.
Van Aert said: “I thought ‘let it be over as soon as possible’, because it was no longer heartfelt.
“Whether I am disappointed? Yes and no. There was no more to it and I didn’t make any mistakes, but I had hoped for a better feeling.
“This was the main goal of my spring. I just need to recover from this.”
Van Aert missed out on the 2020 Tour of Flanders title by millimetres as he was beaten in a two-rider sprint by Van der Poel.
After winning Ghent-Wevelgem earlier this season, Van Aert’s next chance of a one-day victory will be in Brabantse Pijl on April 14, followed by Amstel Gold Race on April 18.