What do boys mean by Happy Tanabata?

Hello, let me answer your question. If a boy only says Happy Tanabata to the only girl, it means that the boy has a certain affection for this girl, because he is the only one who says Happy Tanabata to him, but not to the second girl. You know, Tanabata is not another common solar term. Tanabata is the day when cowherd and weaver girl meet. Of course, this is a fairy tale, but for us humans, this solar term means mutual love. So when a boy says Happy Tanabata to the only girl, it means that he must have a good impression on this girl and like him. Of course, it may also be a polite greeting, but the former is bigger than the latter's idea. Well, the above is purely a personal answer. If there is any similarity, it is purely personal experience. Finally, I wish you a happy life!