The 31-year-old was delisted by the Power earlier this week after 193 games with the club, first making his debut in 2009.
Speaking on Triple M, the West Adelaide product said it was an arduous reality to come to terms with.
"It's been a difficult two or three days," Hartlett said.
"You invest so much time and effort into a club and when you don't get the ultimate reward that everyone's seeking with a premiership I guess there is a sense of unfulfillment.
"That's been a difficult one to swallow I guess."
Hartlett made just the 10 appearances for the Power this season, with his last match coming against the Suns in Round 14 as a medical sub.
As the 2021 season narrowed to a conclusion, speculation surrounding Hartlett's future had already begun, with his name being linked to Gold Coast.
Hartlett revealed that he and his agent have made contact with the Suns, a concept the Queensland club are mulling over.
"We’ve reached out to them (Gold Coast), my management and I, just to see where they’re at," Hartlett said.
"There are still some things to work through there.
"Gold Coast aren’t entirely sold on that idea just yet I suppose, but they’ve certainly said they’ll keep it in mind.
"I know there's been a lot of rumours floating around on social media that's signed, sealed and delivered. I can assure you that it's absolutely not at this point."
Gold Coast are also believed to be willing to part ways with their first-round draft selection, which is placed as the third overall in the 2021 Draft.
The Power have also ramped up their trade season, with Giants forward Jeremy Finlayson reportedly holding a medical at Alberton, while Port have confirmed their interest in wantaway Swan Jordan Dawson.