My husband’s mother’s family is all Italian-American. They are the most warm, loving, and loyal people I know. To our knowledge, only his great-aunt (one out of five) was cheated on (her husband had another family - he also had mafia connections.) The cheating had nothing to do with him being Italian. It had to do with him not showing proper respect for his wife and family, and being a criminal thug.
Ethnicity does not determine behavior. Culture can have a strong influence, and it may be possible that your local Italian community may be incredibly insular and that it teaches men that this is an appropriate way to treat women. But to try and place the “blame” on a person’s supposed, not even confirmed, ethnic background is “stretching it” at a minimum.