Its a shock

Well during the time where taeju and euihyun were just yk the fuck buddies or whatever they were, taeju always wears a condom and he also clearly stated before that he didn't want to have sa baby but later when he realized his feelings for euihyun somehow taeju's rut also aligned to that so yeah no condom and also no consent sex was done so baby was made (=・ω・=)