Mind of an addict speaking here, but I'm facing the same thing, only in reverse... in a relationship that I know is not sustainable given my history.
I'd like to think that love transcends all, if it's truly realized. But I also know that there is a rational element to the success of a relationship as well. I think both of these things need to be kept in mind for a healthy relationship, whether it's a first date, or one of 30 years.
I can't tell you who a person is, or how they will act, any more than I can predict what color underpants I will wear tomorrow. But I do know that for me, my history has determined my present. I'd love to wine and dine a date, but I can't. And if it got to that point, I'd feel some pretty deep reservations about commitment, because as an alcoholic, I haven't even been able to commit to myself.
Now, this is me... and only me. I don't want to paint all RAs with the same brush because everyone's tale is different. But my background leads me to believe that this should be thoroughly evaluated on a continuous basis. Relationships are always two ways.
So, as others have echoed, I would push for open discussion, and maybe a truthful self-assessment of their time sober.
Wishing the best...
RS