The Hollywood pair started dating in 2003 during a whirlwind romance and they married two years later.
Reformed Lothario Kutcher fell straight into a serious relationship with Moore and asked the actress and her three daughters to move in with him just days after their first meeting. But his home was still targeted by fans turning up at his front door unannounced.
Now, Kutcher reveals it was his stubborn roommate who helped drive the wanton women away.
He tells British TV host Graham Norton, "It was really quick. I was sort of going out and having my fun and being extremely single ... and then I met Demi and within about two weeks she moved into my bachelor pad that I was living in with a buddy of mine and my buddy refused to move out.
"But (I) didn't just move her in, she moved in [with] my three now stepdaughters ... this was after about two weeks, a week and a half. She was moving to Los Angeles and she was going to rent a house so I was like, 'Why would you rent a house? Just come stay with me.' And then I didn't really think about the fact, I mean my buddy and I had been living in this house for a while and he really refused to leave. But it was kind of a good thing because it would be the middle of the night ... and there would be strangers coming up and ringing the doorbell to come have a visit and he would do a lot of intercepting for me that was very, very handy ... It takes a while to slow that train down!
"[I was] trying to keep my relationship with Demi private because we don't want all the press and we managed to do it for a month but you know, in keeping it private I couldn't like send out a memo to everyone. So my buddy would kind of curb people at the door and it kinda worked out. Eight years later [we're still together.] In Hollywood terms that's like 81 [years]!"