Why would a guy I was with all the sudden stop talking to me? without even breaking it off?

I was with a guy for about two months. I basically lived at his house and one day after me staying at his place for a week and half. He dropped me off and said hed pick me up later on that night. He then stopped talking to me completly. Do guys do this a lot? We didn’t fight, and he just that day told me cares for a lot and wanted to take it serious. I’ve tried asking him what happened and he hasn’t said one word. Didn’t answer a text message at all?