The first time I watched Sarah with a black lover, I shot my load as soon as she started to suck him. I had stopped wanking about 30 seconds before, but I still shot my load.
The next couple of times I watched I still cum early and at that point wanted it all to stop.
I then mastered edging myself and could last till the end when he cum.
The only exception, was the first time she went bare with her long term lover. We had planned it. For 4 days before the meeting Sarah had been edging me 4 or 5 times a day. Then on the day, I could not touch myself, for fear of cumming. Her lover then cum inside her for the first time and I had sloppy seconds. I literally entered her and I cum, within seconds!