Just watched the movie and question? (Spoiler Alert)

It is my understanding that a sex addict has NO control over their libido and will literally do anything sexually w/anyone. Question: If this is the case......why

When Diamond invited Zoe to join her and Quinton in sex, turning it into a menage a tois wouldn't Zoe have been game? I kept waiting for her to do something really kinky, dangerous or out of the ordinary sexually to show just how craven her addiction had made her but all she really did was have an affair w/2 guys. I guess the sex club and sex in the bath room was pretty bad but still......