Personally I would stay away but that’s just me. I guess you just have to decide if the risk is worth it. Especially if you don’t think it would work out in the long run. How bad would you feel if he gave it to you and then you two ended it? Now you have herpes and no boyfriend.
He could still pass it along to you even when he isn't having a break out. It’s not ALL that rare, and as for a vaccine I'm not sure how much faith I would put in that.