Based on just this, I would say that no faith is a true faith! Since not a single human being is immune to committing adultery and sadly, there are many witnesses who have committed adultery and thus, brings shame on Jehovah!
However, happily, faith does not hinge on just whether one stays pure in their marriage!
Many people twist scripture and your example shows that.
I think of another, where we read: and if you keep looking at a woman, you are committing adultery in your heart. Many could twist that and say: ah well it is ok for a woman to commit adultery, because that scripture clearly states that it is a man who keeps looking!
It all comes down to love. When one loves Jehovah with all their hearts, that helps to keep from doing things that displease him.
So ones who defect, show their love for Jehovah is very weak!
I do apologise for not actually ANSWERING your question. I have not heard of this person and to be honest, do not care, because it is hard enough as it is, to keep strong in this horrid system!