I wouldn't be surprised that the writer added Bidulgi couple breakup. Jun wan was always dating someone throughout his whole life. He also started his relationship with Ik Sun only after breaking up someone else. He feels alone easily so he always wanted someone to share his life with, which Ik Sun fails to do so at first. But luckily as this is a drama they get back together.
As for IkSong couple they are just too involved with other matters. Well to begin with Ik Jun is a newly single dad and he wouldn't have wanted Uju to feel burned by his love life. (May have been). And Song Hwa is already busy with her life. I was so surprised by the Song Hwa's denial to Ik Jun's confession. May be she needed some reassurance that her 22 year old crush / friendship is worth it and it will make both of them happy. I guess Looney's advice made her realize that. I should appreciate Ik Jun's patience. He was so patient with Song Hwa throughout the whole drama.
1 
https://www.kpopmap.com/6-differences-between-the-kings-affection-k-drama-and-webtoon/
https://www.instagram.com/p/CWW1LvNLOo6/?utm_medium=copy_link
https://www.kpopmap.com/6-differences-between-the-kings-affection-k-drama-and-webtoon/
As for IkSong couple they are just too involved with other matters. Well to begin with Ik Jun is a newly single dad and he wouldn't have wanted Uju to feel burned by his love life. (May have been). And Song Hwa is already busy with her life. I was so surprised by the Song Hwa's denial to Ik Jun's confession. May be she needed some reassurance that her 22 year old crush / friendship is worth it and it will make both of them happy. I guess Looney's advice made her realize that. I should appreciate Ik Jun's patience. He was so patient with Song Hwa throughout the whole drama.
https://youtu.be/-lBwQFM4ci8
😂😂😂