The Seagulls led 2-0 at half-time with goals from Anthony Knockaert and Yves Bissouma. Marc Pugh got a goal back just before the hour but Florin Andone ensured Brighton would progress when he headed home the third just nine minutes later.
On the defeat, Howe said: "It follows a pattern of recent weeks. For 25 minutes/half an hour I thought we were fine. We probably didn't break them down well enough and ask enough questions of the goalkeeper but we were fine in the game and then suddenly with their first shot on target they score. We then wobble and concede again, and from then on it's a tough afternoon.
"Games always swing on small moments. We hadn't created an abundance of chances but the one that came before the first goal was a key moment in the match.
"It's just been us in the last few weeks. We haven't been clinical at one end and haven't maximised our chances. It's easier to score at the other, and that needs to change.
"We are going to go away and work on the training ground for the first time in a long time and try to put everything right.
"You learn in every game. Everyone is learning on the job. There are no excuses. We both made changes. We just weren't good enough at both ends of the pitch again. "
Howe also spoke about new signings Nathaniel Clyne, who made his debut after joining on loan from Liverpool, and Dominic Solanke, who has signed from Liverpool, and said: "It was a good performance from Nathaniel. It's very difficult when he hasn't had a training session with your team mates but he fitted in well. He was defensively excellent.
"We needed a right-back with the injuries we've had to Simon Francis and Adam Smith, so as soon as the window opened, we looked to strengthen. Nathaniel was the obvious candidate, as a player of huge experience and undoubted ability.
"Solanke will bring a different dynamic. Good physical presence. All round, he's a very good player but will miss most of January with a minor hamstring problem.
"It's a lot of money but he's one of the most talented young players in the country, there's no doubt about that.
"We have a good environment, good culture which will hopefully get the best out of them (Clyne and Solanke). I'm looking forward to working with him and am looking to develop the player, the individual and the person.
"It's difficult to say whether we are going to do more business. We're looking at different areas."
HAVE YOU READ?