The Brit has been in charge of the Milton Keynes-based outfit since their inception into Formula 1 back in 2005 and has won seven drivers' championships and six constructors' titles with the team in that time.
Verstappen shares a close relationship with his father Jos, who also raced in F1 for eight seasons between 1994-2003, claiming two podiums.
Horner's deteriorating Verstappen relationship
Now, it's being reported that Horner's relationship with the Verstappen family was 'badly damaged', even before these allegations against the 50-year-old were made public.
Dutch publication Motorsport Total.com have said that three-time world champion Verstappen is very loyal to his close circle of friends and family, and that Horner may no longer be a part of that.
They have inferred that the Brit has not seen eye-to-eye with Verstappen senior for some time, and even alleged that it is 'probably no coincidence' that the 'inappropriate behaviour' allegations were first reported by Dutch media.