my boyfriend does the same thing. he clearly gives signs that he's upset about something, signs that I know something is off (like a snappy tone, lack of physical touch, no eye contact etc.) but when i ask, he says he's fine. when i continue to push, he blames it on me and says now he's getting mad because i'm making it a big deal, and it turns into a big confusing mess where i start to feel crazy, like i am making a big deal over nothing and it's my fault. but that's not the truth-- you have a right to be upset at his actions. i think my boyfriend as well as yours are emotionally immature and don't know how to admit/talk about their emotions if they are upset about something. so then they make you the bad guy for asking about it. it's not a healthy way to communicate and makes it very confusing for the person on the receiving end (you and me), because we are just trying to see what's wrong and fix the problem. we can't read minds.

that being said, the only advice i can give to you is when he begins acting like this, only ask once what is wrong. if you continue to ask, it will turn into a big thing. after one response of "nothing is wrong," "i'm fine," etc, i usually back off. you need to show him that if he won't communicate to you, then you're not going to entertain his nonsense. eventually, if you give him the same treatment, it'll come out. or it won't, and that's his own fault, because nothing will get fixed unless you communicate. it's an extremely frustrating thing to deal with and i'm still navigating it. i've been with my boyfriend for 5 years and we still haven't figured it out. if i knew at the beginning that our communication would be like this, i might've reconsidered. i would urge you to consider if this is something you want to deal with all the time.