Responses
There are chapters before this chapter where they have done it without protection because Seolhyun insists on Hwa not wearing one. Hwa worry that he will get Seolhyun pregnant but Seolhyun believes he’s a male so he didn’t care. He thought he can’t be pregnant. They have actually done it without protections many times before.
The blood thing probably realized that hwa’s semen is in him so he stopped