Thanks everyone for your answers. Yes, I don't want to cross the friend zone and I'm perfectly good being in my clothes, in fact I prefer them on. But, I can't say No (I know I should, but I can't say it for long) more than twice. Moreover, I'm not uncomfortable being naked. I've told him that he doesn't raise any sexual desire in me and neither will ever be able to. I've tried moving away but he goes into depression and I find it difficult to see him in depressed state.

I get I'm at mistake here. Thanks again