The Reds were beaten 3-0 at Anfield - marking a sixth defeat of the season for the Premier League title holders.
Van Dijk said afterwards: "We concede too many easy goals. I think in the first half an hour we were good, created good opportunities. They scored obviously from a set-piece again; you can ask yourself if he was in front of Alisson, but it counted so you're 1-0 down.
"I think overall we were just not good in terms of the battles, the challenges, the second-ball fight. Too rushed. It's a very, very difficult situation at the moment. It was a tough day.
"There is nervousness after we conceded but not during that particular moment. You sense that you want to rush things after we conceded, trying to find the equaliser as soon as possible. That's human when you're in a difficult moment. I don't think there is nervousness before a set-piece, we cleared the ones before. In the end, obviously we're just in a very, very difficult moment and we have to get out of this.
"But you don't get out of it just by speaking about it. Like I've said many times, I'm obviously here speaking to you guys because I have to, I'd rather sort it out with my team on the pitch. That will take a lot of hard work by the looks of it."
On Anfield emptying well before the final whistle, Van Dijk added: "I can't decide obviously what the supporters are doing. If they leave early, obviously I can understand the frustration fully. But I know the fans have been through thick and thin with us over all those years and that's how Liverpool is.
"I'm pretty sure that they will always stick with us regardless. And when we come out of this - because we will come out of this - they will be there with us as well."