The Sheffield golfer admitted he played a little too safe as he carded a one under par 71.
The overnight leader, Fitzpatrick struggled to make headway on what was a steady round of golf and ultimately finished two shots behind winner Francesco Molinari.
In contrast, Molinari surged up the leaderboard on the final day with an eight under par round 64.
“I did feel like I should have won the way I played, so I am disappointed I lost by two,” Fitzpatrick said.
“And I can think of two things where I could have hit a couple of better shots maybe, but overall I just think it was just a little disappointing.
“I probably played too safe. I think sort of protecting my position a little bit.
“I'm delighted for solo second, but I just felt like the way I played and the way I was hitting it I could have been a little more aggressive.”
The Sheffield golfer's chances were hit with a bogey on the 15th and although he took the shot back on the 16th, he was left with too much to do to overhaul Molinari.
And Fitzpatrick will be looking to shake off the disappointment as he heads to The Players Championship at Sawgrass, starting on Thursday, along with fellow Sheffield golfer Danny Willett, who missed the cut at Bay Hill.
“It's one of those I sort of stood over shots sort of wanting to go maybe, two, three yards close to the flag and so me and Billy were sort of discussing about going two yards further away, which hindsight is a pain and I wish I had not done it,” Fitzpatrick added.
“But at the moment in time you don't want to drop shots.
“Obviously if I dropped two shots, I dropped 10 places, that's how it is out here.
“It's just one of those things where I just think looking back feeling the way I was playing and the way I was hitting the ball, just wish I had maybe been a little bit more aggressive.”
Playing partner Rory McIlroy took plenty of the spotlight as he started the day one behind Fitzpatrick but he also failed to make any ground.
The day was all about Molinari, who started in 16th place and five off the lead but finished two clear to take the win.