The novel has extra stories, like him about to take on another women because he was getting pressure to produce and heir. The queen encourage him (but secretly hated it) he really really didn't want to to select another women, but since the queen was telling him to do it for the sake of an heir, he felt like he had no choice. The queen was actually the one in charge of going through canadiates for him (I felt bad for her while readinbg because I thought they had their HEA)....but in the process of selecting a candidate, the queen found out she was pregnant and that she was actually not infértil, the person who performed the health check up in the beginning lied (can't remember why). Once the mining and her  finds out she is pregnant, they cancel then process of finding someone to produce an heir. I believe they have twins, and there are sides stories of them, I think. But the manhwa looks like didn't produce the remaining bits of the novel.