After some help understanding my friend

Hi! I have a very dear friend who I care about a lot that I would like to understand better so I can be a better friend. I suspect he has Asperger’s, and me having ADHD, well I overthink a lot haha and so sometimes I worry he doesn’t like me. He’s just very quiet around me. He can talk mostly fine with everyone else, but with me he is so quiet. He will agree to come hang out with me, yet when we’re together he will hardly talk and so I start to worry he doesn’t want to be there. But then I will think well he wouldn’t have agreed to come hang out with me if he didn’t want to… Is it possible that he feels more comfortable around me and so is just happy to hang together in quiet? Sort of like dropping the masking and allowing himself to just be because he doesn’t feel pressure to mask? I’d like to hope it’s that, and if it is, I will feel more comfortable myself and happy to just chill together in quiet. I just don’t want to make him feel uncomfortable. I want to be a safe space for him so if he’s happy being quiet with me, that’s ok with me. My ADHD just makes me overthink and worry I’m doing something wrong because the thing is, he used to talk a lot more. It’s just over the last few months he has become very quiet. He talks more when we are with a mutual friend group still, but he used to talk more when it was just us. Now he barely says anything and yeh, I worry I did something wrong. Yet he will still stay around and hang with me after other friends have left and when he does leave, he will say talk to you later, and I’m left thinking but we barely talked! As I said, I’m happy to chill in quiet. I don’t really have people I can do that with and my ADHD means I often need quiet because I get overstimulated very easily. I just want him to be happy too so thought I’d come here for some insight and advice. Thank you in advance! ❤️