Am I right in saying if he leaves you on unread, he isn't interested?

If you are hooking up with a guy - he works in your local shop so you see him nearly everyday (chat a little) but when you message him on whatsapp he only messages for a while and then leaves you on unread for a day or two, does that mean he isn't genuinely interested in you? (He said he doesn't like to message much but you can see him online)
Am I right in saying if he leaves you on unread, he isn't interested?
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