Did he use me?

So me and one of friends had sex about 2 months ago but things have been a little different between us. We don't talk as much, far as us hanging out we don't do that as much because of our work schedule but we've gone from texting each other everyday on and off all day to me barely hearing from him since we did that. It's like I'll text him on my down time but won't get response until hours later. He works from home so I know he can look at his phone more plus I see him repost stuff on his social media. I'm starting to think that now we did that our friendship is over. We've been friends for like two years maybe 3 and we only had sex just recently and that was twice in one day. Should I just leave him alone or try to figure out what's going on.