Why are guys so confusing!?

So I dated this guy for a month and then he broke up with me. We had a better relationship as friends so we’re still talking. We had sex while we dated and we had sex 2 times after we broke up. Yesterday was the 3rd time we had sex and for some reason today he decides to be short while we are texting. I tried to keep the conversation going but he would just keep being so short with one word answers and then he just left me on open on Snapchat. Why does he do this the day after we have sex!? And what gets me mad is that i still have feelings for him...