"You've got to draw the line in the sand somewhere, and that was mine."
The $8.2 million building was officially opened in late September after a long journey since the idea was proposed in 2013.
The project's budget was blown out significantly, eventually costing almost double what was originally set aside.
Dunn said the decision to resign wasn't one made lightly.
"It's been a real hard one for me. I've been on council for one and a bit terms, and of course, sometimes you've got to make those hard calls as a councillor. I knew the expectations of the community, but I just couldn't endorse the building knowing myself it wasn't right.
"Under the circumstances, I just didn't feel I could carry on and do the job well."
Despite the challenges, Dunn had nothing but positive things to say about the Bulls community as well as one of her council colleagues in particular.
"I loved working with the Bulls community. They're a real good lot on the whole and I got a lot of support there."
"I also want to thank (Bulls ward councillor) Brian Carter. He gave me all of his support and he will continue to do great things for Bulls."
Carter himself said that he learnt a lot from Dunn and was sad to see her leaving, particularly after mentoring him in his role as a councillor.
"Jane was a big asset around the community centre and a lot of other projects around the place. It's saddening to see her leave on these sort of circumstances."
Carter said the community did have concerns with the end result of the project but had confidence the council would resolve any issues.
"There are concerns with the result of the build, but the council is working their way through the different bits and pieces - but it just wasn't happening fast enough for Jane.
"You always expect more than what you're given, but I agree the result of the centre could have been better I feel."
Mayor Andy Watson has been approached for comment.
According to the council website, a by-election will be held in early 2021 to determine Dunn's replacement, with voting taking place from an undetermined date in January, closing on February 17. Nominations will be called for later this month.
The council has been approached for comment on what the by-election will cost.