How to ask a FWB to be more...

Bri 🌺✨ • 21
So there's this guy I hook up with often. I wouldn't even call him a fwb since its usually long periods of times we go without hooking up and I'll hookup with other guys sometimes. But I'm starting to be more interested in him and kind of like him... He treats me better than most guys I've been with and I feel safe when I'm with him. I want to ask him if he wants to do something one night but I don't know how to come about it without scaring him or looking desperate. I'm not good with things like this, so any advice?