Boris Johnson has again declined to discuss in detail the late-night quarrel at his home, saying it was "simply unfair" to "drag" his loved ones into the political arena.
The Tory leadership frontrunner was involved in a spat in the early hours of Friday morning, which saw police called by worried neighbours after his partner was heard screaming and shouting "get off me".
Mr Johnson held out on making any statement about the row in his partner's flat for three days, but has finally answered questions in an exclusive with the BBC's Political Editor Laura Kuenssberg.
When asked what happened that night by Kuenssberg, Mr Johnson said he did not want to "drag" his family and loved ones into the political arena.
He said: "I...would love to tell you about all sorts of things Laura, but I've made it a rule over many, many years and I think you've interviewed me loads of times, I do not talk about stuff involving my family, my loved ones.
"And there's a very good reason for that. That is that, if you do, you drag them into things that, really is, is, in a way that is not fair on them."
Mr Johnson was asked whether privacy meant more to him than public trust and responded: "Yes I get that, I totally get that.
"But my key point though is that the minute you start talking about your family or your loved ones, you involve them in a debate that is it is simply unfair on them."
The issue of a photograph of the couple that emerged at the weekend was raised, with Kuenssberg suggesting the former mayor of London could be "trying to have this both ways".
Mr Johnson dodged the question, saying "I just do not go into this stuff" and referring back to "innumerable statements I gave when I was mayor".
He said: "Actually I think what people want to know is what is going on with this guy, does he, when it comes to trust, when it comes to character all those things, does he deliver what he says he's going to deliver?
"And that is the key thing."
Kuenssberg agreed trust was key and suggested the Tory membership would be looking at his record when deciding whether to vote for him and warned "there are plenty of people even in the Conservative Party who worry that you do not stick to what you promise".
But Mr Johnson dismissed this, saying: "Well I think they're talking absolute nonsense.
"When I was mayor, when I became mayor of London, when we said we would do something, we, I may say delivered not just X but X plus 10."