Yes, I could see myself involved in what you describe. And there are woman who have problems with their sexual organs who can’t have penetrative sex without pain and it sounds perfect for them. But if you are going down on her, the relationship is not platonic. A Platonic relationship is one with no romance and no sex of any kind. There is a misunderstanding the world over that penetrative sex is the only real sex. But there is a whole range of sexual and erotic behaviors that do not involve the male sex organ.