A 'soft launch' is hinting at a new relationship on social media without confirming it — posting a photo of a partner's hand, the back of their head, or an extra place at the table. It contrasts with a 'hard launch' (clear, confirmed reveal). If your teen does a soft launch, they are signalling something privately without going public. Harmless; reflects modern privacy management. Also has a business sense (quiet product release before full launch) which predates the dating use.