Steve Cooper apologised to Swansea City’s fans as he pledged to continue building for the future following play-off defeat to Brentford.
Swansea’s bid for the Premier League ended as a 3-1 loss at Griffin Park saw them beaten 3-2 on aggregate.
Cooper felt some uncharacteristically poor defending cost his side a chance of reaching Wembley.
“With everybody’s hopes up tonight, I am sorry we couldn’t get over the line,” he said.
“I am sorry we didn’t get the job done tonight because I really thought we could and we would and I know the players thought that as well.
“I am proud of the lads keeping going at the end and not giving up and fighting for the football club, but we know we gave ourselves too much to do.
“We came into the game positively. We did nothing different. But we just fell short on the stuff that we ask for every single game.”
Cooper said the thrills of Swansea’s final-day win at Reading, when they claimed a play-off place in the dying minutes of the season, seemed “a mile away” after goals from Ollie Watkins, Emiliano Marcondes and Bryan Mbeumo saw Brentford through.
Rhian Brewster pulled one back for Swansea but the Bees held on to set up a play-off final against either Fulham or Cardiff City, who meet in their second leg on Thursday night.
“Tonight’s a really disappointing night but we do know that we’re building and looking into the future a little bit,” Cooper added.
“We will stick to that plan. Preparations are already in place for next season, but it’s disappointing at the moment.”
Brewster, Freddie Woodman, Marc Guehi, Ben Wilmot, Aldo Kalulu and Conor Gallagher are all now due to return to parent clubs after loan spells at Swansea, although Chelsea defender Guehi is expected to return for next season.
Swansea also hope to secure a fresh loan for Woodman, while it remains to be seen whether they have any chance of re-signing the likes of Gallagher and Brewster.
The Swans also have five senior players out of contract in Erwin Mulder, Kyle Naughton, Mike van der Hoorn, Nathan Dyer and Wayne Routledge.
When asked whether some players have worn the Swansea shirt for the last time, Cooper said: “I think so – most probably. We need to have discussions with some players over the next couple of days.”