I don't know how guarded/expressive you are but were I you I'd "test" him a bit by paying attention to his responses after some of your own actions/words? When he says something, call him on it or get more enthusiastic than you normally would, etc. and see if the next interchange changes him? Or get iffy, not sure if you're interested in getting married (especially to him?) and see if he bumps up his mood to make you interested?