I think explaining to your friend that you still think of them as your friend even if you don’t talk much is very important I love my friend/roommate through highschool and university and we once had a fall out because they thought we weren’t really friends since we don’t chat much ( but we do movie nights and eat together when we can ) And I got really upset about it, but somehow thought okay maybe we should talk it out. So I told them that I find it hard to maintain communications but I consider them my very close friend. We talked it out, and they understand now and I understand them better. We’re closer after talking so I think communication is key even if it’s not frequent.

I think some advices would be : - remember to ask questions about them ( it’s easy to forget to do that and I found that it keeps the friendship strong ) but also be careful to not delve too much ( asking about interests is a safe topic ) - if you’re comfy, tell them about your adhd and explain how that can affect the relationship - try to talk to them about things you’re interested in ( it’s easier to talk about those and hey it’s a hack to talk ) - tell them how important they are to you ( if not by talking maybe a gift or a gesture )

I’m sorry this is all I’ve got since I’m still figuring it out, I hope it helps !