The Bleeding House (2011)

A couple makes out.

It is implied that a woman was having an affair.

It's a serial killer movie. Most of the deaths are with blunt force trauma to the head, such as a hammer, or a candlestick. The most gruesome is when a women's head is visibly bashed in with a rock. Several people also have their throat slit. This is usually done up close. A gun fight also occurs but it is off screen. There are also stabbings. One of the most visual scenes is when a man sews up a knife wound. There is an extended instance in which two people have blood drained out of their bodies.

Surprisingly very little, but it covers the traditional spectrum.

A couple that is supposed to be in their late teens/early twenties drinks liquor. The woman is seen smoking a cigarette.

The movie is a horror/thriller and maintains a level of eerie intensity throughout.