I'm a little confused..

My boyfriend just said that he want us to wait to we get married to have sex.. But I mean I wouldn't have had a problem with that if that was established when we first dating, but that isn't the case... & then I asked him why or what what his reasoning for it and he's not telling me anything.. I'm so confused right now & kind of sad, I don't know how I should feel right now 🙄😐😪 is that a good thing or bad. Am I wrong for being mad at him? What should I say?