Humphreys miss is a right kick in the teeth for Ulster
Munster let off the hook after late fightback from Doak's warriors just falls short
It ended dramatically with Ulster having a shot at winning a game which looked to have got beyond them, but this time their battling qualities were denied as Munster held on to triumph with Ian Humphreys' missed conversion giving the visitors the result.
In a frantic final 10 minutes, Ulster - under the cosh for so much of the half - came back from being 21-12 behind and looking down and out to score eight unanswered points through a Humphreys penalty and Nick Williams try against a 14-man Munster who had lost Stephen Archer to the bin.
However, the conversion of Williams' 79th minute score was missed by Humphreys - who otherwise had a strong game - and with it the chance to win this interprovincial clash right at the end to give Ulster an ideal boost going into next week's European double-header against the Scarlets.
Instead, Neil Doak's squad had to be contented with a losing bonus point from only their second PRO12 defeat in this campaign.
Of particular concern for Ulster will be the fact that they were in total control of the game and led 12-0 after only 20 minutes thanks to four Humphreys penalties. But ill-discipline and a drop in intensity allowed the home side recover from trailing 12-8 at half-time to lead 21-12 with just over 20 minutes to go through tries from Robin Copeland and Duncan Williams and 11 points from the boot of Ian Keatley.
Humphreys ended the evening scoring five penalties but just couldn't land that last minute conversion.
It was Humphreys who got things going with a third minute penalty and he added a second in the 10th minute.
Three minutes later and after Paddy Butler had blocked a high kick chase from Gilroy, the penalty was awarded and Humphreys landed the longer range kick to give the visitors a nine point lead without response. That became 12 when Donncha O'Callaghan was pinged offside and Humphreys nailed a wonderful penalty.
The home side now just had to get back into the game and did so after an Ulster mistake gave Munster a foothold in their opponents' territory and an apparent high tackle from Gilroy allowed Keatley to get his side on the scoreboard after 23 minutes.
Ulster then launched a good attack which ended up with a penalty being given away after Nick Williams threw the ball at Butler's face. The net result was a wonderful inside pass from Duncan Williams which propelled Ronan O'Mahony through a hole and after a recycle, Denis Hurley put Robin Copeland over on the half hour.
The scoring pass looked forward but the score was given and Munster had closed Ulster's lead to 12-8 at the break.
Munster came out with all guns firing in the second half and Duncan Williams slid over for a try three minutes in. It was a bizarre enough score as Copeland missed the pick-up and Williams then took the ball after Paul Marshall had slipped and the Munster scrum-half burst blind into unguarded territory and slid through Gilroy and the scrambling Marshall's tackles to ground in the corner.
The 43rd minute try - given the all-clear by the TMO - put Munster in the lead for the first time and Keatley then got the touchline conversion to put them 15-12 in the lead.
It was all Munster now and eight minutes later, Ulster - now increasingly ill-disciplined - were pinged for dragging a lineout maul down and Keatley did the needful to put his side six points ahead at 18-12.
Then after Sean Reidy was tackled and possession legally sealed off by Hurley, Keatley landed a superb penalty to put Munster 21-12 up after 54 minutes.
Munster then upped the ante and after a superb break from Keatley, the out-half then was in position to grubber kick in behind Ulster over the try line and JJ Hanrahan appeared to beat Stuart Olding to the touchdown.
The TMO was consulted and the score ruled out as Hanrahan was adjudged to have a leg over the dead ball line. It was a rare stroke of fortune to go Ulster's way but referee Ian Davies brought play back for a Munster penalty and Keatley put the ball into the corner.
Ulster, though, defended the attempted driving maul well and forced a knock-on to relieve the pressure near their line but, from the scrum, replacement Declan Fitzpatrick was pinged though Keatley's penalty it the upright and bounced out.
The tide then suddenly turned and Ulster managed to get themselves into Munster's 22 from a useful Darren Cave kick through and from the lineout Stephen Archer was sin-binned and Humphreys landed the 71st minute penalty for Ulster's first points of the half.
After winning a scrum penalty deep in Munster territory, Humphreys put the ball in the corner with two minutes remaining and Ulster launched a maul which made it over the line with bodies everywhere.
The TMO had to be consulted after a pile-up at the corner flag and with no try given an earlier penalty for pulling down the maul was given. Again Ulster went for the corner and Williams got over with the TMO having no problem with it.
That meant it all fell to Humphreys but he hit it wide and though Ulster threw everything at it, they agonisingly fell short.