What does stick out in my mind was how he concluded. He said that as a Rabbi he receives a lot of phone calls from women and his wife takes the calls, gives him the phone and asks no questions. How is this possible he said?? Would an average wife be completely non-suspicious of a husband who has women calling him on the phone all the time??
The answer is, he explained, that his wife knows how careful he is about halacha - yichud, negiyah, kol isha etc. His wife knows that because of all the halachic barriers and her husbands yiras shomayim she can trust him. It's a package deal. If one keeps all of the halachos which may seem extreme at times it will almost ensure that he will remain pure. The halacha knows what it's talking about.
Fast forward twenty years. I am not a big Rav like Rabbi Frand but whatever I am I get a lot of emails and at times phone calls from females. What I find remarkable is that my wife, like Mrs. Frand, doesn't ever seem the least bit suspicious and is completely not interested in who I am talking to and why. The explanation is that I also keep all of the "extreme" laws of tzniyus so my wife knows she can trust me. I wonder at times if I can trust myself but I am assured that keeping all of the halachic boundaries and working on my level of ruchniyus with lots of mussar will ensure that I will be successful where so many others have failed.
Sweetest friends! We all have "modern" friends who are more lax than we are. Don't envy them - they are playing with fire.