Is he in it just for the sex or is there more

So this guy I hooked up with a couple of times asked if he could have a threesome with me and one of my friends. I don't know why he asked but I think he was testing me, to see if I liked him or not. Thing is he is very shy, but I've noticed a lot of signs that he likes me but he seems scared to make a move. Like he always randomly shows up at places that I'm usually at, but he'll act as though he didn't see me only to later mention it when we're together. He remembers everything I say, even the most trivial of things. Also i'll catch him staring and then he'll quickly look down when he sees that I saw him. And when there's other girls, my friends for instance, he'll talk to them and ignore me. 'm confused 'cause he once mentioned that he liked me but that wa ages ago and his signals are confusing. Now, I've started to like him as well but I am not sure if I should tell him or not 'cause he might just want sex and nothing more