Storyline is about a girl who visits a mansion and fall in love with owner who thruns ointo beast at night

Beauty and the Beast... the TV series with Linda Hamilton?

Meridian (1990)
Aka Meridian: Kiss of the Beast
Starring Sherilyn Fenn, Malcolm Jamieson, Charlie Spradling
IMDb synopsis:
Two American students go to Italy after graduating from art school: one to work in restoration of paintings; the other because she's inherited her father's castle. When the restorer visits her friend at the castle, they invite the players of a traveling sideshow to dinner and are slipped drugs, leading to an orgy of abandon. The woman who owns the castle keeps having visions of a young woman who has been stabbed in the castle. After talking to her nanny, she finds that the "vision" woman is her father's sister, who was murdered brutally as the consequence of a 15th century curse put on her family and that she is the next in line, and the troupe they have entertained is a part of the curse.

IMDb review excerpt:
She and her friend have been drugged and ended up getting raped by the ringleader and a mysterious masked man, who not only is the twin of the ringleader of the freaks but also turns into some sort of beast mid-coitus.

Meridian (Video 1990) - IMDb