Hmm. This is more complicated than I originally thought. While I want to say absolutely not, I am also in the type of relationship where both my s/o and I would offer to pay each other's debt in a heartbeat. We do our money together, and work to pay off both of our debts. Although our relationship was pretty instant and we knew we were spending our lives together after 2 days of talking. 

So...I'll change my answer to: it depends on the person and their financial habits, how much debt, how long the relationship has been going on, and if you're 100% certain that you will marry the person.