The 68-year-old rocker said he is now a changed man and claimed he was constantly "looking for that perfect woman" when he was younger.
He revealed to the Daily Telegraph newspaper: "It was a long time ago. I was loyal to Rachel for seven years, and I've been with Penny for 13.
"I think I was always looking for that perfect woman, who obviously doesn't exist. I wanted to be married. I wanted more kids. I'm a family man, at heart."
Still, Stewart did admit he doesn't think many men would have behaved differently, given similar "opportunities".
He said: "I was shagging my way round the world, like most blokes probably would if they had my opportunities."
- Bang! Showbiz