The Tigers' 25-9 Heineken Cup final defeat by Wasps was Howard's final game in charge before returning to Australia to run his family's pharmacy business.
After five long years without silverware, Leicester finally emerged from their barren spell this season by winning the Guinness Premiership and EDF Energy Cup.
They seemed well positioned to add European glory to that roll of honour only to be thwarted by a bone-crunching display from Wasps, who extended their winning run in Twickenham finals to a remarkable sixth straight victory.
The Heineken Cup final has added another gripping chapter to English club rugby's fiercest rivalry of the professional era, but Howard has no sense of unfinished business.
"I've made the right decision and it's time to go. I've loved the club and I've loved the players as well," said the former Wallaby.
"I've been lucky to be involved in this club and in the Heineken Cup but it's time to walk away. I can't say never again but it's right to walk away at this moment."
It was the first all-Premiership Heineken Cup final and while there were too many errors for it to be a classic, the contest was utterly absorbing.
The mystery is how players who perform heroics in a Wasps or Leicester shirt wilt for England on the Test stage with the world champions enduring a another wretched season.
However, Howard heads down under believing that club and country are in rude health.
"English rugby is in good shape. I'd like to take a really positive tone on where the sport is in this country," he said.
"It's a good product with good teams and good players. A lot of clubs are doing things the right way - not just one or two but many.
"The team that got relegated beat us in the EDF Energy Cup so that shows how strong the competition is. The sport is doing well."
The treble may have been a bridge too far for Leicester and could ultimately prove beyond any club, even one with the resources enjoyed at Welford Road.