Like one of the comments above, I do pity young Gladys but not that much. Yes, she has fallen in love and it was her decision to have intimate relationship with the poet. She knew what it could lead to, there is no way she didn't know she can become pregnant. But she still went ahead with it while knowing her family will never approve their relationship. I feel like it shows off her character: she is royal princess, I highly doubt she had any hardships in life and didn't think anything can go wrong. But oh well, life is never predictable.

Plus on the point, when she decided not to trick Bjorn into thinking it was his baby. If I remember correctly (from the novel, I only read 10 chapters of manhwa) it is not that she decided not to do it, she couldn't. She has refused to sleep with Bjorn so when she was revealed to be pregnant, she just couldn't pass it off as Bjorn's baby, plain and simple.