What do do...

I need some advice...Four weeks and he's using four letter words... Fastest time before that a boy said it in 6 weeks and after 6 years it turned out it was a lie. How can you know so quickly? I guess if I don't know it isn't the same for me. I've told him I don't know...Question now...Do I wait to figure out how I feel or cut him loose? I don't want to lead anyone on if I'm not sure.