Niall McGinn scored the only goal of the match 14 minutes from time as the away side moved above Hibernian into second place
Hibs would have gone top of the SPL had they won, with Celtic losing to Inverness, and Fenlon admitted he was hugely frustrated not to win the game, let alone lose it.
"Results elsewhere don't really come into it." Fenlon said. "We didn't deserve to lose the game today.
"It feels worse than last week (a 3-1 defeat to Dundee) because we didn't deserve anything out of that, but this week we deserved to win. Even a draw I think would have been a travesty.
"Their keeper (Jamie Langfield) was fantastic today, particularly the save he made from Eoin Doyle in the first half.
"I'm not sure exactly how many shots Leigh Griffiths has had but again the goalkeeper has made some great saves.
"We have to take it on the chin and move on."