Most Helpful Guy
i think you could take a passive aggressive approach by just changing conversation to subjects that are clearly platonic. like don't talk about dating, sex, relationship interests and all that stuff
or you could just put it out there sort of like, "look I could be totally reading things wrong and if I am I'm sorry. but I don't want to lead you on or lead this relationship in a direction that gets to a place where things get weird. I really appreciate you as a friend and all but I don't have feelings for you. I want to be up front since I respect you and don't want you wasting your time on something that most likely won't happen"