The law of domestic partnerships is new, in rapid flux, and likely to change a lot in the near future. For a description and some basics, see the Domestic Partnerships page of our web site, posted at http://www.willicklawgroup.com/domestic_partnerships.
A complete answer as to the treatment of debt in either such a partnership or marriage is beyond what can done in an e-mail, but there are articles addressing debt division in the marital relationship in the articles posted on the Published Works page of our firm web site, at http://www.willicklawgroup.com/published_works. The short version is that pre-marital debt remains the debt of only the person who owes it, but post-marital income and property could end up being used, in part, to satisfy those obligations.
You should probably seek consultation with an appropriate family law specialist. I would suggest starting your search with the American Academy of Matrimonial Lawyers, the Nevada chapter of which can be viewed at http://www.aaml.org/go/fellows/fellows-by-state/?showResults=true&state=NV. Good luck.