我没料到这个无耻的女人居然同她好友的丈夫调情。

[误] I had not expected that this shameful woman should flirt with her best friend's husband.

[正] I had not expected that this shameless woman should flirt with her best friend's husband.

注：shameful 通常指某事物是“可耻的，丢脸的”，而 shameless 表示 having or showing no feeling of shame;
immodest or impudent,它一般用来指人“不知羞耻的，不要脸的”或“伤风败俗的”。

原文也可译为：It's shameful that the woman should flirt with her best friend's husband.