Unfortunately that happens a lot and is just rude, your idea while it has merit is impossible to set up
as all they need to do is leave the room, close the achat or shut down pc.
i would suggest that you just place that person on your ignore list and never think about them again
there are selfish people on here as in real life , given time you will find the partners that are more
concerned with your pleasure than theirs these are the ones you select as lovers and you will
eventually have a stable of partners that will satisfy you and vice versa.
i would add thats sometimes the real life happens i had friends walk into my house while i have been
so occupied or something in real life intrudes and i have had to bail immediately but an apology
goes a long way towards to healing bruised feeling and disappointment.
Wishing you good luck, just remember there are good people out there as well as arseholes