Why are there people complaining that someone they are dating is tossing one off to them..

I guess it depends on the context. If you're having a sexual conversation and they rub one out then it would be somewhat appropriate. It might feel a bit weird if they did it while you were talking about your day at work, lol 😂

I used to jerk off thinking about my wife all the time before we started dating she used to date my mate and I always wondered what she looked like naked

If I were a woman I think I would be rather chuffed that some man fancies me enough to want to wank over me....