What is the Islamic way to counter Sihr (magic)?

I suspect somebody has cast evil spill on my son and his wife. Although they married out of their own willingness, their marriage is in tatters 1 year into their marriage. My son apparently didn't have sex with her for months and treated her very badly. She says she no longer loves him and doesn't want to see his face. Our family is close to collapse, is there an Islamic way to find out if sihr is involved? And how can I find a Muslim scholar to help us. I just don't want to get involved with people involved in satanic rituals who work under the guise of Islamic scholars. *Please help my family*.