Grace Slick and Jim Morrison dated during The Doors European Tour (Germany, London, Copenhagen and Amsterdam) in September 1968 as Jefferson Airplane was playing with The Doors.
Jefferson Airplane started their European tour with The Doors in London, at the Round House, located at the end of a railway line. The Doors were making an excellent performance, all was black except a spotlight on Jim`s face, there was a special atmosphere there and Grace saw it all from the backstage.
Grace took a very good time talking with all the members of the both bands, The Doors and Jefferson Airplane, but with Jim Morrison, they had non-sense dialogues with a very pupils dilated Jim Morrison. All their conversations had non-sense and she never knew which could be his answer.
She remembers one night very nervous standing in front of Jim Morrison`s hotel room, it was daylight and Grace knocked at the door with Airplane`s "secret knock", and without asking anything, he opened the door and he smiled. They went on to the bed and started to play games with some strawberries that were in a dish in Jim`s room. Grace remebers to being laughing a lot and having a lot of fun. Suddently Jim stood up and stared at Grace.
She recalls: "I`d never had anyone "study" me like that. It wasn`t the standard evaluation of body parts. He seemed to be apparising the distance between us as if it was an invisible garment that needed to be continually breached with each motion. With our hips joined together and his body moving up and down, it felt like he was taking a moment each time to circle the area between our bodies with his eyes and consider the space that separated us. He was a well-built boy, his cock was slightly larger than average, and he was young enough to maintain the engorged silent connection right through the residue of chemicals that can threaten erection. At the same time he was surprisingly gentle."
Grace Slick at that time had other relationship (so Jim had) and she left the room as fast as she could.
She was never asked again to get in Jim`s room, so she didn`t came in again, but she remembers having a good time with him in that tour. It was the sixties, the free love era.
Source: "Somebody to Love?: A Rock and Roll Memoir" by Grace Slick and Andrea Cagan