The Alliance Party is not a "cold house" for unionists, its Belfast city leader has insisted after a colleague defected to the UUP.
Councillor Nuala McAllister said she was "saddened" by Carole Howard's departure and "disappointed" over first learning of it in the media.
She questioned whether Ms Howard was "always suited to the Alliance Party" as her comments since quitting suggested the "driving force behind her politics was the constitutional question".
Ms McAllister, Alliance's group leader on Belfast City Council, said party reps are able to express either pro-Union or Irish unity views but they choose not to.
In a wide-ranging interview, she also revealed she felt "ashamed and disgusted" over launching a proposed hotel named after George Best upon learning of the footballer's history of alleged domestic abuse.
The former lord mayor said that "we need to call out all male violence in all its forms".
And she called for a "sea change" in tackling violence against women in the wake of the killing of Ashling Murphy.
When Ms Howard announced her switch to the Ulster Unionists last month, the Belfast councillor said she could now "openly and comfortably" express her pro-Union views.
Speaking to Belfast Live about the defection, Ms McAllister said: "Alliance is not a cold house for unionists.
"I deeply regret and I dislike that saying because everyone knows that in Alliance there are people from many different backgrounds, many different walks of life who do have differing opinions on the Union, on the constitutional question.
"But that's not what drives us in Alliance. What drives us all in Alliance, regardless of what view you may or may not have, is that we want to create a shared future."
Asked if Alliance reps can express pro-Union or Irish unity opinions, she responded: "People are able to express their views but they don't, and I think that says something better.. because it's not something that they think about every day."
She added: "I think to be honest the real question here is, was Carole always suited to the Alliance Party, and that's something that you need to ask her.
"But it seems from what she has put out in the media that actually the driving force behind her politics was the constitutional question. That's simply not the case for Alliance and for us in our party.
"Our policy will be that where there are conversations that we have to have, we have to engage in those respectfully."
Reflecting on the outpouring of grief across Ireland over the killing of 23-year-old teacher Ashling Murphy in Co Offaly, Ms McAllister called for greater efforts to tackle violence of all forms against women.
She said: "I'm very proud of my party leader Naomi Long in her role as Justice Minister and everything that she is doing through legislation to actually tackle violence against women - and that's domestic violence as well, but also sexual abuse too."
As lord mayor in 2017, Ms McAllister helped launch early proposals by a Liverpool developer to create the George Best Hotel in Belfast city centre.
The plans have since stalled, but Ms McAllister expressed regret at her involvement in the launch event after subsequently learning of the late footballer's alleged domestic abuse against his former wife Alex.
"I was actually ashamed and disgusted that I had done that," she said.
"I'm not aware of every sports personality, every celebrity. It's not something that I have great knowledge of, and I was actually ashamed and disgusted that I didn't look further."
She said she would act differently today.
"We need to call out all male violence in all its forms whether it's a celebrity, whether it's someone within your own family, whether it's a friend," she said.
"We need to actually be able and feel comfortable to step out and say we shouldn't support these people, we shouldn't see them as these great personalities or whatnot."
Polls suggest the Alliance Party could significantly increase its vote share and number of seats in the Assembly election in May.
Ms McAllister, the party's North Belfast candidate, said that if Alliance does well there would need to be a reconsideration of how Stormont power-sharing operates.
She said it would be "undemocratic" if her party was denied some ministerial posts because they do not designate in the Assembly as unionist or nationalist.
The councillor said the titles of the first and deputy first minsters should be changed to "Joint First Ministers" and the system of MLAs designating as "nationalist", "unionist" or "other" should be scrapped.
But on returning to government she said her party was "not demanding red lines".
She added: "We should have power-sharing agreement not by force but by choice because we believe that we can be mature enough to do that."
As families face soaring food and energy costs, councils will soon be making decisions on their rates.
Ms McAllister said a decision in Belfast is due next month.
"As always Belfast is very proud to keep any rate increase below the rate of inflation but that decision hasn't taken place yet," she said.
"For Alliance though, one thing that we have always been clear is that if we are going to ask people in Belfast to pay extra in their rates, whether it's pennies or pounds, because every penny does matter to people, we need to make sure to tell them what we can show for it.
"Because people need to make sure that we're delivering for them."
