Relationship problems🤷🏼‍♀️

i don't know what to do I feel like my boyfriend is acting different. Everytime I ask him if he's okay he says yea but, I know there is something off. He acts like he's rarely interested in me all of a sudden. I know he wants to have sex with me badly but we haven't been dating long and I don't want to yet. Ahhh helpp!!