That appears to be the allegation. No doubt more will come out in court.
I note that he was charged in 2024, that the offences are alleged to have taken place in Woodstock, that Blenheim Palace is in Woodstock and that Wikipedia says that the Duke and Duchess separated in 2024. All purely coincidental I'm sure.
The court hearing has been adjourned until January, but legal papers show that the charges do indeed relate to alleged offences against his estranged wife Edla, Duchess of Marlborough. Here they are in happier times:

Duke of Marlborough accused of strangling estranged wife
The 70-year-old is accused of attacking Edla Marlborough in Oxfordshire between 2022 and 2024.
