A goal by James Vaughan just before the interval had cancelled out Leonardo Ulloa's opener for the Seagulls, but the Argentinian went on to grab a hat-trick in a 4-1 success.
Brighton's second goal followed a corner which Robins was convinced should never have been awarded.
He said: "For 74 minutes I thought we'd get something from the game.
"But it wasn't a corner and then we conceded. We can't blame the referee but the second goal led to a capitulation.
"The two goals that followed came as a result of us thinking about the misfortune we suffered. Up to then Brighton hadn't hurt us very much.
"We had taken four points in our previous two games and we wanted another point or three, but it was unfortunate we conceded when we did."
The Terriers have won only three times in the league since the turn of the year and Robins said it was essential they bounce back, being only five points above the drop zone.
He added: "We've got a lot of work to do and not a lot of time left, we've only got two months. For large spells of the game we did okay but we have to bounce back.
"We will certainly go forward. We have 11 games left and we're after as many points as possible. We also have some players coming back from injury and that will help us."