Most Helpful Guy
It could be that he is simply an introvert. My ex hated that I was not a texter nor did I call her often. I also refused to see her at least once a week (I saw her five to six days a week a guy needs a break sometimes) So I would say he just likes being alone sometimes, its not personal, introverts are like that. For me being around people is enjoyable but draining, if I am around people to long I start getting tired and burnt out. So I would say don't worry about it.
Most Helpful Girl
You never know. I had a guy who was attentive, not much for texting and calling and he was flirting online just a step away from physically cheating which he claims he never did but who knows now. Then I had a guy who was attentive with me and without me and he ended up being an idiot too. At the end you have to go with your intuition just don't confuse it with paranoia though.