I've had this before in the past.
A happy ending was DEFINITELY on offer from her, but some SPs like to be asked, rather than to ask. If only you had!

Years ago I used to see a black girl (bizarrely) in a Chinese massage place somewhere in the East End. She did a really good pukka massage and on the first visit we got talking like you do, and she was after a job in the industry I was in. I gave away loads of info about myself and then later I realised that extras would probably be on offer. I never felt as though I could ask, so was waiting for her to.
I ended up going straight to her house in Dagenham to cut out the middleman so to speak, and I'd have a truly wonderful massage for £30 for a whole hour. She did exactly the same things you described, and I'd be laying there with a massive hard-on and she would whip off the towel fully exposing me, while she similarly went deep into my groin. She was a tiny little thing with enormous tits (I never worked out whether they were God-given) and she would lean over me from behind my head...I thought I'd gone blind and deaf

.
She'd always leave me 5mins to cool off and get dressed after the massage, and one time I was so horny I knocked one out as soon as she left the room. I was kinda hoping she'd come in and catch me
in flagrante but she didn't. I wonder whether she was looking through the keyhole?
In all the times she massaged me, the anticipation was overwhelming, which of course is very sexy. But at the same time, in this case, immensely frustrating!
