All is going well but why did he suddenly stop talking to me?

A week after we've met in personal, he sent me a DM. And since then, we talked a lot. We work in the same office but only meet once or twice a week based on our schedules. He initiated most of the conversations in personal and in chat. And just as I thought that he's interested, it suddenly became quiet after a couple of weeks. He suddenly stopped talking with me in chat. We would still meet though. But I don't know how I'd feel. Why would a guy make me feel as if he's interested and then suddenly withdraw? Or were our interactions really didn't have any meaning?

All is going well but why did he suddenly stop talking to me?
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