Hi - Rob has stated in the Italian Vanity Fair magazine that he is single.
He says “I am single… almost everything that came out about my private life is false.”
I believe this was (sorry I couldn't watch the link) from the Today Show when Rob was speaking with Matt Lauer...I believe they we're discussing the rumors and being 'snarky' about it because of course Matt was referring to the Kristen Stewart rumors. I think Rob said that yes all the rumors were true...so it was clever of Matt & Rob to run down all the other crazy rumors in that same breath as Rob also confirmed that yes indeed he also died of a drug overdose *sarcasm*.
Both Rob & Kristen are really good at not directly answering questions about their relationship other than what is obviously an extremely close friendship.