The Reds suffered only their second Premier League loss of the season, going down 3-1 after a testing contest at Emirates Stadium.
Van Dijk felt that the key moment came in the 67th minute, when a mix-up involving the captain and goalkeeper Alisson Becker allowed Gabriel Martinelli to give the Gunners what proved to be a decisive lead.
Leandro Trossard went on to wrap up the points in stoppage time after Ibrahima Konate had been shown a second yellow card for Liverpool.
Speaking to Sky Sports after the game, Van Dijk stated: “Eventually [it was] a very tough day, definitely. I think the 2-1 goal, I take full responsibility for that, but it’s a big turning point in the game.
“I should have done better, I should have made a better decision there. It hurts for me, and it hurts for the rest of the team. It was a big turning point in the game because I think especially after the break, we were so good.
“We had opportunities, we were dominant and I think the atmosphere started to become a little bit more nervous. Arsenal is a very good team and they will always try to stay in the game, but we were very dominant, especially in the second half.
“And then came the turning point. It’s my responsibility. I should just clear it, but I made the split-second wrong decision and unfortunately these things happen sometimes in football. But that doesn’t take away from the fact that it hurts.
“These things haven’t happened too many times in my career but it’s a tough one. I will recover from this because I will learn from things that don’t go well, but I will take the responsibility.
“I’m not looking for excuses. At the highest level, it’s a split-second decision that you make. I chose to let the ball bounce and put my body in between. Alisson touched me a little and that’s why he couldn’t clear it.
“Things happen, and I take full responsibility for this. I will try to make sure these things don’t happen.”
Despite the result, Liverpool remain two points clear at the top of the Premier League and Van Dijk added: “It’s our first defeat since September. Obviously losing hurts, especially with the way we did it today. In so many ways it was unnecessary, but we take it game by game.
“Like I said, it hurts for me, seeing all the fans coming all the way down. It’s not nice to be involved in mistakes, but I will be back. There’s no doubt about that. I will make sure these things don’t happen anymore.”
