Personally, NTPs I have no problem with. I quite like them. NTJs, I'm known to not get along with so well, though.
But, yes, romantically speaking, I don't think they should be paired. Do we make good friends with eachother? Absolutly! But romantic partners? No. Don't see it happening. (Except maybe INFP with INTP, I can see.)
Of course, there are many NT-NF relationships that work out very well. It all just depends on the individuals and how well they can handle eachother's weaknesses. If the NT can learn to be more soft when criticizing an NF, and if an NF can learn to not be so fluffy, then I think they get along fine.