honestly this is gonna be kind of insulting to say probably but literally just write what you want. it's a lot harder than it sounds. there's a reason your instincts and your familiarity with the characters/dynamics you're writing and the story you're telling are saying you want x to happen, so maybe just. let x happen? as an example i had a scene in a fic i was working on where character A tripped and character B caught them before they could fall. my first instinct was to have a detail where A's clothing slipped a bit in the process and B brushed their bare skin and this was Significant. but bc the relationship is platonic i didn't want it to seem weird and like i was implying something or hinting at something with that. so i almost took it out, rewrote the detail as B's thumb getting caught in a twist of A's shirt. but i didn't. because a lot of that story is specifically ABOUT intimacy and touch and skin contact and navigating that in the context of a platonic (in this case burgeoning queerplatonic) relationship. so that first instinct was right, i just had to like. talk myself back into it after initially balking.

remind yourself that platonic relationships are not blank slates onto which romance is invited to be projected, even though fandom treats them that way. platonic relationships are just as intentional and fully realized and specific and worthwhile in their depiction as romantic relationships are, and they get to take up that space too.

remember that if people get weird about it, that is a them problem. they are the ones making it weird. if they decide to force romance into a relationship that is not indicated that way, that's on them, and you can't be blamed for it.

i often include a specific disclaimer about a dynamic i am particularly worried about, or whenever this anxiety gets too strong for me and starts upsetting me. i will put in the beginning notes of a fic 'as a reminder this is a gen fic/my depiction of the relationship between A and B is platonic! please respect that' or something along those lines. if someone ignores that, i block without hesitation, or i respond with 'this is a weird thing to say to someone who made it very clear this is a gen fic/platonic relationship'. i have spent a lot of time trying to teach myself that i get to have boundaries about this. but it is weird and shitty for people to make ship commentary on non-ship fanwork and i wish that was a more widely understood/accepted thing.

remember, above all, that this is important to you for one reason or another, and also it's probably important to other people too. one of the things that gives me the most courage and determination in writing about things the way that i do, especially relationships, is the number of times people have expressed to me that this is meaningful to them, too. that the way i write about relationships, intimacy, affection, connection, longing, touch, etc, is very valuable and important and even healing for them to see in a platonic context. i won't lie, people have said some weird shit to me about the way i write. they have gotten aggressive and mean and arophobic etc at me. that's one of the tough things about this. i have ocd but, unlike an anon who yelled at me about this the other day would have you believe, it's not solely mental illness that has me really anxious about this. people do say and do the shit i'm afraid of and wanting to avoid when i write about platonic intimacy. but that is far, far outweighed by the people who have been lovely and extremely moved by what i've written, and that matters so much more to me.