Yeah this entire situation/relationship sounds like treading on some serious thin ice. Tread lightly, but don't be tricked by his BS. It sounds to me like he is just blowing you off and not taking it seriously, and there are some opiate addicts out there that simply do not really care about ever quitting......sad, but true.
I actually started abusing opiates with an ex GF.......I know all about this road, if you start doing them too then all hell will break loose, it is basically a matter of fact. But if it is simple curiosity that you want to try them......didn't you already say you have tried them before and didn't like them? If you force yourself to take drugs you don't enjoy that is also twisted.
I just see a kind of one sided thing emerging here, its a shame but it is often this way in relationships where opiates are present, especially with younger people.