I can see that others have already offered their opinions, so I'm hoping to build on these responses and hopefully give you a few things to think about.
It makes me happy to hear that you're very accepting and supportive of him and his identity, and that he feels like he can trust you with deeply personal information like this. That's amazing to have in a relationship. As somebody who started being open about my bisexuality right before getting into a relationship with my current boyfriend, I can empathise with both you and your boyfriend and recognise how you must both be feeling. My boyfriend occasionally asks whether I'm bothered that I haven't gotten an opportunity to explore my attraction to women, so I understand your situation.
It sounds like a great idea to have another talk about your future together: where you see the relationship heading long-term, your individual future plans, and how the relationship may adapt if or once you end up moving away. If he's comfortable talking openly about it, I would also raise his sexuality, and whether or not he wishes to explore this at some point. If he does want to explore but still wants to stay with you, I'd have a talk with him about how this would work in a way that respects both your boundaries and his. It may even be a good idea for him to open up to another trusted person, like a friend or family member, so he has the support of a few people. I know that personally, the more people I opened up to about my bisexuality, the more comfortable and supported I felt. I also agree with Smallwolf, in that it's probably wise to open up to another trusted person yourself, provided that your boyfriend is okay with you discussing his sexuality with someone else.
I wish you well in this situation and hope things work out for the best between you and your boyfriend. It sounds to me like you have a great relationship built upon mutual trust and respect, which is fantastic.
I'm always here to talk more if you need.