New to dating.

So i have only dated one guy like 8 years ago. We got married, fast forward i've been single 2 going in 3 years. I recently started trying again. I met what I thought was a great guy. He seemed worth a chance. We had a date monday and he was acting strange when he left. Didn't want to talk to me me on the phone on his way home. Barely text Tuesday, a few more yesterday, and none today :-(. Before monday everything was great. I have no idea what changed. He won't talk to me about it. Communication is very important to me. Any suggestions?