help :(

okay, I've been talking to this guy and we're hanging out New Year's <a href="">Eve</a> at a party, when we first started talking he was super sweet and we talked for like the whole day the past few weeks. he says I don't annoy him but he randomly will read my message and stop replying. should I ask him what's wrong? or leave him alone. he said he liked me I'm just confused what happened.