Guy's Behavior

Why would he ask to keep contact only not to maintain contact?

Last week I went on a date. It was incredibly enjoyable and I stayed over to spend the night with him. In fact, I had my first kiss from this guy, and he knew about that.
Anyway, we live on opposite sides of the world and the next day I went back home.
At night he texted me because he felt sad about me leaving and hoped we could stay in contact.
Then when I asked why he was still awake, he told me it was because he couldn't sleep - he felt like he was going to miss me.
He told me multiple times he was afraid I would forget about him and so I made it a point to reach out to him to keep the contact going.
I've been home for some time now and I've noticed that even though he was the one to suggest keeping contact, wanting to see me again, expressing how he would miss me, etc. he also rarely responds to my messages and never keeps a conversation going.
When I asked if he wanted me to text him at all, he told me I could text him whenever and even though his responses seem encouraging of maintaining contact, he never actually reached out himself or even tries to hold a conversation. Usually it's just one message, so I always feel reluctant to keep things going.
I don't really know what to do about this and if it's even worth keeping contact if he's already losing interest in trying to stay in touch just few days after I left the country.
Is this a normal thing to do? What is the reason for such behaviour?
Why would he ask to keep contact only not to maintain contact?
Post Opinion