He wasn't conscious about it
He himself was shocked by what he did
No justification tho , but yeah ....
I would say that it's a conscious effort, because he always wear condom, even when he's affected by Hyesung's heat, so why suddenly he forgot about it now? And also if you read the translation post here, one of them explain that Dojin knowingly use his pheromones on hyesung in ch 18. Don't get me wrong, I still love Dojin, but Mama don't approve of his method this time. Their first child shouldn't be a rape baby.
SPOILER ALERT
No mean in the rows he breaks it pretty quickly
Hate to say this but I think so
Bruh but he breaks that promise so damn quickly