Why send text messages? Sometimes he replies to every message, and sometimes he doesn't reply to every message. Why?

Sometimes when he is happy and bored, he will reply to every text message.

But sometimes he gets upset. Even if I'm bored, I won't return. . Or have other things to do. . He won't reply either, but he replied to your message anyway.

It means that he just likes you, but he doesn't love you enough. . .