I miss someone inexplicably. Why did I just know her (the dance teacher in the fitness center) for a while and only added WeChat, but nothing happened?

This teacher must have something that attracts you, or looks or talent or temperament. It is normal for a person to be remembered for his greatness. Compared with you, you are at the age of falling in love with the seeds of love. It is normal to attract the first opposite sex. If you think it's possible for you two to be together, you have to pursue it hard. If the gap is too big, then think about it!