The loss leaves Liverpool outside the top four, as they collapsed 2-1 at Brighton on Saturday.
"Disappointed. We wanted to win, which is important in this situation we are in but it didn’t go that way, so it’s a difficult afternoon," Gakpo said afterwards.
“Frustrating. I think it’s happened a few times already this season. It’s not good from our side.
"Not really (why the inconsistency), if we knew, then we would try to solve it. But like you said, it has happened a few times already, so we have to analyse it to try to find what’s been hurting us.
"I think they (Brighton) were just being themselves. Everyone knows how good they can be on the ball; they tried to play their own game and it worked out well in moments for them."
On needing to win seven games for Champions League qualification, Gakpo added: “Approach every game like we are going to win it. I think that is normal for a club this big, and I think that’s also what we are supposed to do when we are in this situation like this.
"We have to fight to win seven games."