To know what he's feeling you'd have to ask him. Don't think it's overstepping or rude to ask him questions about it because you deserve to know just as much as he deserves to be himself around you. It may lift some weight off his shoulders to know you truly care for him but don't be surprised if he's reserved about it at first. He might not want to deep dive so soon into the relationship and that's okay. Keep being yourself and open to communication and things will work out just fine. Stuttering is a bitch and you can take a scroll through this sub to know a little of what he goes through on a daily basis. Not all PWS (people who stutter) are the same just like anyone else. So to know him best yoy must ask him but don't push for answers. Im not speaking for anyone but I appreciate you being active in learning and Im sure he does too. Hope this helps.