Is it over?

I have been dating this great guy for about 4 months now and I think I love him. But lately I've been feeling like things aren't the same between us. He lives an hour and a half away from me and has a six year old son so I only get to see him every other weekend. We talk most days but the conversation seems to have lagged a lot lately. I noticed on Twitter he was making plans to have drinks with another woman. I am a teacher and I start work next week so I'd prefer he just break it off now than wait until I'm back at work. This upcoming weekend is supposed to be an "us" weekend and he seems reluctant to commit to spending time together. He works two jobs and spends as much time as possible with his son so he may just want some downtime but I've just got this nagging feeling that something is up. I do suffer from anxiety though and tend to read too much into things. Thoughts? Advice?