The model married her ''soul-mate,'' Doug, 53, when she was just 16, but now thinks she was too young for their relationship to work out.
She said: ''I think the age difference is 99.99 per cent of it. I think I missed the experience of being youthful and being single.''
The US TV personality admitted she found it hard to come to terms with the fact her marriage to the 'Green Mile' actor wasn't working.
She said: ''I wouldn't say my marriage got bad. Doug and I were in love, but over time that love shifted into something that wasn't romantic anymore.''
The 19-year-old star claims their split was amicable and Doug remains one of her managers.
She added to new! magazine: ''I was unhappy and with me being unhappy, Doug was unhappy ... We kind of came to the decision [to split] mutually, which is really nice because we remain the best of friends.''
Courtney has also told how Doug wasn't satisfying her needs in the bedroom and how she's looking forward to meeting new men, despite still living with her soon-to-be ex-husband.
She said: ''Our sex was good, I'm not going to lie, but I'm a young girl who wants to experience sex of all kinds and he's an older man who's slowing down a bit. I wanted more sex.
''We weren't having sex at all. When I came back from 'Celebrity Big Brother' [in the UK], we did it once and that was it.''
Courtney added that being in the reality TV house without Doug was one of the things which made her realise her marriage was on the rocks.
She said: ''It was like my only chance to go crazy and feel single, and I was trying to get it out of my system before I left the house so I could go back to Doug and be happy.''
This Doctor won't be saying 'goodbye' in the same way as those who have left the series in recent years.