Old professor and his sister-in-law

The professor sees his wife’s sister having sex with his hunky student against the back of a pickup truck through his house’s second floor window. Could be a vision. Later..The professor has sex with his wife in front of fireplace, but sometimes, due to supernatural effect, he sees his sister-in-law riding him instead of his wife. While the professor is in the shower, his sister-in-law enters the shower and starts having sex with him. Another vision?