There was this girl I worked with, and we were just friends. After knowing her for several months, I'd call her and we'd just talk, but it was obvious that she just wanted to be friends, so I didn't try anything. But she would tell me sexy things and I would get aroused.
I started masturbating while we talked on the phone. At first I would be really quiet about it, but after a while I started letting her hear me. To my surprise she never mentioned it or stopped me. Eventually we'd go to dinner and return to her place and talk or watch TV.
After years of this and a lot of teasing, I decided to just tell her one night that I was going to her bathroom to masturbate. She just said ok and let me. After a few nights of that she said that I should just sit there and masturbate while we watched TV! She didn't want to do anything, but she'd let me masturbate next to her.
Whenever I was over she would tell me to strip, and I'd masturbate all evening, just walking naked around her house. She never wanted to have any sex, but she seemed to take great delight in keeping me hard. She'd tease me and ask me if it felt good, and tell me not to cum until a certain time. This was always fun but after a few years she moved away. We sometimes talk, but not very often.