Conversations with boyfriend

My boyfriend and I have been together for over 2 years and I know that by this time, relationships aren't new anymore so things change. But things changed and we barely talk much anymore. He can't ever keep a conversation going and I thought maybe it's because we spend more time together. Right now I'm away for the summer and when we text, he still can't keep a convo. I'll try to talk about something and he just kills the convo by sending a one word answer. I tried to talk to him about this before and I feel like he just isn't putting in the effort. Is it because we talk/text all the time and we need more space? Or is it just time to move on? I have no idea if our chemistry is gone or not. He still wants to have sex with me and all that, but I'm just getting bored of our conversations.