I have TN, what are options for CDN GF?

I am starting work on a newly issued TN early next year. My girlfriend wants to come live with me while I am down in the states. She doesn't really want to do much besides hang out on my days off, etc.
Does anyone have any experience with having their partner be denied at the border if they have only the intention to visit and hang out?
Any other stories along these lines would be appreciated.

Many thanks.

As a Canadian, she can visit the US for up to 6 months, but she won't be able to stay the entire year duration of your TN visa. It is likely however that she'd be denied entry if she has severed all ties with Canada in order to be with you in the US.

If you two get married, she'd qualify for a derivative TD visa, but she is not eligible as a girlfriend. The US does not recognize common-law marriage like Canada does.