I am not really sure that this is the root of the problem. I personally do not hold so much of the psychological approaches. I do agree that this is an addiction and therefore it should be dealt with in this manner, and I agree with you that there are certain "triggers" that set it off,but if we start at the beginning, we see that the ribbono shel olam gave us an unbelievable Taivah. And, we are told to control it!
It is inherint for us to be attracted to the opposite sex so that we will fulfill the mitzvah of periah v'riviah. Chazal were aware that "Arios" were so severe, and that to keep away from this mikshal, they tried to be mevatel the yetzer harah for arios, just like they did with the yetzer harah for avoda zorah. But, as we learn in the gemorah, even the animals stopped reproducing. (I personally don't see why they couldn't just be mevatel the taivah for the arios without losing the healthy desire to fulfill the mitzvah.) Anyway, this has been known from the time of chazal to be an almost uncontrollable taivah. How many yidden perished in the midbar when midyan sent their daughters there to seduce Am Yisroel, until Pinchas came along to rectify the aveirah. I don't believe that they were all suffering like this Patrick Carnes is talking about, i.e. some chilhood psychological disorder from lack of validation. Chazal do speak about not touching your Amah when urinating, not to walk behind a women etc. Why, because it was known what we are dealing with. So all of us here didn't take their advice, and so things got out of control and became addictive.
We have so many examples that this is a very difficult taivah to control throughout our history. (Dovid Hamelech-Bat Shevah)(Yehuda-
Tamar) I do believe that in these cases there were/may have been some devine influence as is found with the avos.
Speaking about free time as a trigger or cause, I remember seeing in the Michtav M'Eliahu (R. Dessler zt"l), that the mind is like a vast empty field. This field will not remain empty. If you do not fill it with good positive thoughts, or busy yourself with something whether it be learning, working etc, the yetzer harah will surely fill all of this empty space. So, if we keep ourselves intellectually busy, there will not remain any empty spaces for the yetzer to fill.