My best friend has very severe ADHD, and his partner does not have it.
How they do planning is his non-ADHD partner (who happens to have a very good planning brain) will basically defines a series of questions that only ever address a very small portion of the task at once. So instead of phrasing open ended questions like "What time do you want to go meet Ryan?", they'll ask things like "Do you want to meet Ryan at 1pm or 2pm?". It a very small change but it helps him break down the decision paralysis that ADHD creates.
It doesn't necessarily address the feeling of letting the other person do all of the planning though- to some degree, that's going to have to be something your partner is comfortable with, unless you yourself can find ways to break down your own decision making into those tiny bite-size chunks.