I suggest reading the description for Eyes of Greed, as it explains what's happening to you.Yes to both... I can only trade right after sex for drugs trade it seems and only once....
All in all, it sounds like you've done a little too much of the corrupt stuff and you're stuck at low willpower.
The solution to Eyes of Greed is to do everything else (like fighting) first and then what purchases you can right before ending the day.