Original Webtoon : https://toptoon.com/weekly/ep_list/Secret_friend
Info : https://www.mangaupdates.com/series.html?id=167202
Alternative Titles : Maidens In-Law or Secret Friend
The translations are app based, so it's not 100% accurate. There will be mistakes.
Synopsis : After 7 years of unrequited love towards Jung Eunkyung who was only interested in Park Kyutae, Park Hyungsoo started to have feelings for his older brother's wife. Besides Jung Eunkyung and Da Boyoung, Hyungsoo felt also attracted towards other women... His sisters-in-law... What choice will he make in a forbidden relationship where everything should be kept secret?