I understand the frusteration--I know it feels like an unrealistic suggestion. But I think it's important to question whether a more general understanding of ADHD could help? Like if people knew that, because you have ADHD, forgetting a date or something is not a sign that you don't care about them as it's out of your control. Maybe people in your life could learn how you express that they are important to you. They could learn to appreciate you for who you are and forgive you for who you are not. I know, for me, I greatly appreciate when someone remembers my birthday or an important date, but I don't hold it against them when they don't/can't.
That's what I mean. It's not reasonable to expect us to conform to every societal expectation when we literally can't, especially when others might have more flexibility to meet us where we are (or even in the middle) and don't currently put in that effort a lot of the time. People could be more aware and compassionate of our condition, just as they won't be mad of someone with a walker can't help them move. It doesn't mean they don't want to help or that they don't care, they just don't have the mobility. People understand that, so why couldn't they understand us, too?