The Qur'an verse relating to polygyny is:
And if you fear that you will not deal justly with the orphan girls, then marry those that please you of [other] women, two or three or four. But if you fear that you will not be just, then [marry only] one or those your right hand possesses. That is more suitable that you may not incline [to injustice]. -- Qur'an 4:3
Generally, this is interpreted to mean that a man is forbidden to marry a second wife if he fears that he would treat them unjustly.
...but if you fear you will not be equitable towards them in terms of their expenses and individual share; then marry only one or restrict yourself to what your right hands own of slavegirls since these do not have the same rights as wives... -- Tafsir al-Jalalayn
However, a Muslim man may not care very much about obeying this command, or may not even be aware of how it applies, and may seek a second wife while being in a situation where he is unable to be just between his wives. I'm wondering what happens if a woman marries him despite being aware of his inability to be just between his wives.
I have in mind a situation where the husband's previous wife will receive the majority (if not all) of his financial support and the majority of this time. She is aware of this before marriage, being informed by her future husband himself and being confirmed through observation of their living conditions. However, she agrees to marry him nevertheless.
Question: If a wife marries an already married man knowing he cannot do justice between his wives, is she blameworthy?
It's unclear to me if she is also engaging in sin, or if this is limited only to her husband.