All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
There is no harm for this woman to investigate and find out what happened to her husband either by asking him directly or by asking other people about him if this does not result in a forbidden matter like being suspicious about him and the like. In principle a Muslim is innocent and we should think good of him/her. Al-Hasan Al-Basri said: ‘A believer looks for excuses [for his brothers] but a hypocrite looks for (their) lapses.’
Therefore, we advise her to invoke Allaah earnestly to rectify her husband and if she is pretty sure that some magic is done to him, then she should advise him to perform Ruqyah or he should go to a person who is known to be righteous and has a correct belief to perform Ruqyah on him. There is no harm also for her to perform Ruqyah on him. In this regard, please refer to Fatwa 88660.
Besides, it is forbidden for a man to work in a place where there are naked women around specially that they are disbelievers in this case and they would not hesitate to commit adultery or fornication with him. Thus, he should be advised to abandon working in these places. His change towards his wife could be a punishment for doing this forbidden work. Indeed a person may encounter many calamities as a result of his sins. Allaah Says (what means): {And whatever strikes you of disaster, it is for what your hands have earned; but He pardons much.}[Quran 42:30].
So, this woman should be patient with her husband as much as possible, but if the marital relationship with him worsens and she fears any harm on herself (i.e. committing adultery), then there is no harm for her to take the matter to the institutions which deal with personal matters of Muslims, like Islamic centres so that they would study the matter and relieve her from the harm afflicted upon her.
Allaah Knows best.