The heiress admitted that she is baffled by rumours that Reinhardt popped the question during a recent dinner date in Los Angeles.
Writing on her online blog, Hilton explained: "I keep getting emails from you guys, calls from family, flowers from friends congratulating me on my engagement.
"They said they read some story the other day, saying that when Doug and I went to dinner with my parents the other night, that he proposed.
"This never happened - I don't know where they come up with these stories sometimes. All we did was have a lovely dinner at my mum's favourite restaurant."
However, the star also hinted that she might be willing to settle down with Reinhardt in the future, revealing that she feels "very lucky" to have found him.
She added: "He's my best friend, we are so much alike, we love to travel and we have the most incredible time together no matter where we are. I've never been happier.
"He truly treats me like his princess and that's how every girl should always be treated. My parents love him too, so I'm really happy about that."
Hilton started dating the baseball player earlier this year following her split from Benji Madden.