Blind sided by my fwb

So me and my co-worker started hooking up a couple months ago. We agreed to be FWB after the first couple "hook ups". Things are great, I go over to his place most of the time because I live with my ex (we're good friends still) and I usually end up crashing at his place and having sex again in the am before he drops me off at home. Well the other day things got kinda rough and my back hurt a little, so he offered to let me sleep in the bed. Which shocked me, he sleeps really light and wakes up suuuuper easy so I usually crash on the couch. I expected him to sleep on the opposite side of the bed, but he actually pulled me over to him so my head was on his chest and we fell asleep like that... Well last night I was at his place playing Mario Cart (as we usually do after sex 😂) and he asked if I wanted to go to the zoo with him. I must have given him a weird look cuz he rambled on about how he likes spending time with me outside of the bedroom too, that I wasn't just a booty call and he was rather fond of me. Which is kind of how I was starting to feel and must have sensed that or something. So we're going to the zoo together in a couple days, I was clear that it wasn't a date. But I'm wondering if that's what he was trying to ask for.

This is my first experience with FWB. Is all of this normal? He's supposed to be my friend too, so doing stuff like that is fine right? How do you keep things from feeling like a date? I know we're not dating, but I keep wondering what the difference is between dating and FWB? We have sex, he's told me before that he cares about me/ is fond of me, and now we're doing things that I would do on a date... If you're attracted to someone and enjoy their company why wouldn't you want to date them? Are there specific things you look for that makes a guy okay for one and not the other? Just curious about other people's opinions/ experiences.