The 27-year-old ex-stripper - who married Katie in 2013 - had affairs with both Jane Pountney and Chrissy Thomas, and Kieran claims he cheated on his wife because both women threw themselves at him.
Asked why he chose to sleep with two of Katie's best friends, Kieran said: ''Because they were easy and they didn't say no, which made them even worse friends to Katie. They could have said no. They didn't have to come and meet me in the car park, they didn't have to have sex with me, but they both did and they're two of Katie's best friends, so it shows you what type of people they are.''
Kieran - who has two children with Katie, 16-month-old son Jett and four-month-old daughter Bunny - has subsequently received treatment for a sex addiction and he's likened both Jane and Chrissy to prostitutes.
In an interview with the new issue of OK! magazine, he said: ''The way they describe it in therapy is that they were basically used as prostitutes without paying for them, as bad as that sounds. Seeing a prostitute isn't really fun as you pay for it and you have it. Chasing someone I wasn't able to get was where I got my kicks.
''I had to deal with the c**p after that went on in my head. There were things that happened when I was younger that affected the way I was. There's been addiction in my family, so it ties in.''
Asked to elaborate on the reasons, Kieran said: ''I'd rather keep that private. I don't think I ever want to talk about it again. I've spoken about it far too much with therapists. I was bullied at school, though, and that's a massive reason why I buffed up when I was older. That's why I got into stripping too, you want to be the bloke who looks good and who women are attracted to, rather than the kid at school being bullied.''
Kieran also insisted his affairs were not motivated exclusively by sex, insisting it was the adrenaline rush of doing something illicit that excited him to seek erotic thrills away from Katie, 36.
He revealed: ''There are three types of sex addictions - those who like sex, those who like porn and those who like the adrenaline of doing something naughty, and I had the third one. People in the UK think of sex addiction as something laughable and it's not taken seriously but now I know more about it.''
Katie also revealed in her mind she has dismissed her wedding to Kieran in the Bahamas in January 2013 and insists the ceremony planned for next month at which they will renew their vows will be their ''real wedding day''.
American Thighs was released on this day in 1994.