Firstly, the fact that you are here asking for advice/feedback on how to approach this speaks volumes as to how much you care about him, so kudos to you for researching about his condition. Stutterers tend to have bouts of highs and lows with their speech. Sometimes it can get to the point of depression and they become more introverted. The frustration can be overwhelming at times for him. Be patient. I would encourage you to speak to him about it when the time is right, and empathise with him. Make him feel supported and he’ll feel more comfortable with you when he talks to you. Heck it could alleviate a lot of the anxiety he has once you both have spoken about it openly together, and this could lead to a road of better fluency for him around you. Good luck! Feel free to ask us anything 👍🏼