Paw my DH was on Warfarin for nearly years after heart surgery and his INR generally kept well under control. It can be a bit of a blunt instrument though and there are more “sophisticated” blood thinners available. At one point we wondered about a change to one of them, but the advantage of Warfarin is that it is almost instantaneously reversible with a Vitamin K shot whereas the newer blood thinners can take up to 24 hours for their effect to be stopped and as DH had Primary Sclerosing Cholangitis and a tendency to gastric bleeds, immediate reversal was crucial.
Try not to worry.
He may have to watch his diet initially as too many dark green veggies broccoli, kale etc) can affect your INR as can oats and porridge. But like all things once you know what to avoid, it is perfectly straightforward.