the prince’s plan is to make FL princess consort even before finding out who she is. In order to do that, he needs to cast a spell as he cums inside a virgin.
A flower-shaped mark forms on the girls’ chest as proof that she was a virgin, and that the magic worked. That’s why this chapter had him talking about “blooming” while the shot lingered on her chest. The spell can only be cast once so the flower mark that results from the spell is really important.