In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
Answering your question, the Fatwa Center at Islam Q and A, states:
If the wife did not refuse completely, such as if she gave in to her husband for fear of making him angry, or she gave in to his pressure, or she was not able to resist her own desire because her husband had provoked it, then in all these cases she is not regarded as having been forced; rather she did it willingly and she has to repent to Allah, may He be glorified and exalted, as well as make up the day and offer expiation.
Sheikh Ibn Baz (may Allah have mercy on him) said:
“She must refuse absolutely, and not let him do that, regardless of whether he gets angry or not.
If they both did that deliberately, then they both must repent and offer expiation, as well as making up that day, and they must repent sincerely for what they have done.
If he forced her and there is no doubt about that, by using his strength and hitting her, or by restraining her, then the sin is on him and there is no blame on her.
But if it is simply a matter of her being reluctant but going along with him, then she is not regarded as having been forced. Rather what she should have done is to refuse completely, for a woman knows how to refuse, unless he compelled her by force to the extent that she had no way of avoiding it, in which case Allah knows that she had no way of avoiding it.”
Almighty Allah knows best.