Clock
I think the whole thing about not wanting to watch the clock is both very important and also totally unimportant. I know that sounds stupid, but let me try to explain my thoughts.
We are all ruled by a clock, by time. Whether it is watching the clock until it is time to go home from work, waiting for an event to happen, waiting for someone to call. In all these circumstances it is always a waiting game, we are waiting for something to happen, or to end. We are waiting to enjoy the time that is ahead, and the time inbetween seems to last forever. However, when we are already enjoying something, then that time seems to pass so quickly.
While Sue is with Brad I'm sure the time passes very quickly indeed, but for you it may seem like an eternity. Wondering if she is going to be late tonight, waiting to get your time together. When she gets home and you are together, then you get the reassurance the she still wants you. You are still her man, she comes back home to you. She doesn't stay with him.
What she is asking is to extend the time she stays with him, by a few hours, and it is only a few hours, and most of them will be spent sleeping.
They are trying to pack as much fun and excitment into the few hours they have together and that can sometimes put a bit of a damper on things. If they have an all nighter, they can relax and enjoy their time together, she will come home more relaxed and have more energy for you.
It will be more frustrating for you, of course, knowing that she is not coming home tonight, but if you can get yourself some sleep, the time may pass more easily. The clock will still be ticking, it always is, but you will still get your time with her.
Maybe you should ask for a phone call the next morning, just to give you some reassurance.
You have not stopped her from doing anything yet, and I think you will come to terms with it. It is only time, and time can be sweet and also bitter sweet.
It all depends if you are enjoying, or waiting.
Hope this helps.