Everyone sucks and I'm tired

I'm so sick of this shit. It's the same fucking thing over and over again. I meet a guy, he seems nice, we go on a few dates, we fuck, and then he tells me he's "not looking for anything serious." Is it that fucking hard to communicate that from the beginning? And when I call them out on it they either blow up on me or block me. It's crazy how quickly they can go from being nice to being an asshole.