I Gyeolhon Gwaenchaneulkkayo?

Dorothea, a bastard princess shunned by everyone, is forced into a fake marriage, practically sold off to the tyrannical Crown Prince of an allied nation, in place of her arrogant older sister. Discovery means certain death! The Crown Prince's proposal: if she bears an heir, he won't interfere with her life. Even before the wedding ceremony, Dorothea finds herself in an intense relationship with him every day. Walking on thin ice, she constantly worries about when she might fall into this bottomless lake... Just then, entering the secret garden of the blue-blooded Crown Prince, Dorothea instinctively realizes: she can no longer escape this relationship!

Original Webtoon:
Ridibooks, Bomtoon, Lezhin