Scene from a 70's softcore movie and another from a horror movie

[MipMipMee]

My post in 2018 didn't get any results but hope springs eternal so I'm trying again.

I saw this movie in the Summer of 1986 when flippng channels on cable TV, likely Cinemax After Dark but I think Showtime also showed movies like this.   The scene I remember is a curly blonde haired guy and a woman with very long dark hair are going at it in bed.  A guy downstairs who is kind of uptight looking is reading a newspaper and getting annoyed at the noise they're making.  It cuts back to upstairs and they roll over and she's lying on top and starts, ahem, "running the show."  The blonde haired guy starts moaning and there's two quick shots, one from the guy's perspective looking up at her with her long hair hanging down, and another of her leg drawn up and toes curled.  The uptight guy gets exasperated and throws down the newspaper and says, "I am leaving!" and goes out the door.  I thought this movie wouldn't be hard to find again but I've never come across it. 

Additional things to narrow it down:

It has a very early 70's look and feel--for a long time I could have sworn it was from "Beyond the Valley of the Dolls" but it wasn't in that movie.

It's an American movie with American actors, not one of the dubbed imports popular at the time.

It has a studio quality feel, not one of those shady 16mmm ones shot in a home or renteed space.

The other move I'm not as concerned on finding, just wondered what the heck it was about.  I saw the first few minutes of it in 1993, and it looked to also be a 70's movie.  A man and a woman are sitting tied together on a motorcycle resting on it's centerstand in a creek or river.  They act like they're in pain as if they were tied with piano wire. At some point the bike falls over in the water and they presumably down, with the intro music and credits showing them floating around underwater.