Thats because K-Pop groups traditionally arent allowed to date and if they are then they might be forbidden from making those details public. Thats because, like most celebrities, K-pop stars are seen as brands and part of the allure of their brand is that its members are (or at least appear to be) single.

Why is BTS not allowed to date?

So, in short, the members of BTS probably arent allowed to date publicly as part of their contracts — although there has been no official confirmation that their contracts include the “no-dating-allowed” clause.