I know I tend to make sarcastic jokes when I feel uncomfortable as a means to buffer the awkward situation.... probably what he's doing since he couldn't lie to you but he probably felt bad telling the truth straight out.
Don't read into it more than it really is. Guys are not like girls where they had double entendres in convoluted words. He said no end of story.
Come one think about it. What guy says to a girl that he loves and wants to be with and see a future with a straight out no. If there are any meaning behind it you won't lose any chances of it going away by interpreting what he's saying as what he is really meaning. Trust me, if a guy wants you he wants you.