Is honesty the best policy? Always

Honesty – Is it really the best policy?

My wife and were talking about a friend of hers who learned that her husband strayed.  I mentioned to her that I sometimes have thoughts when I see a particularly tight butt, just the right eyes or have an engaging conversation about nothing with another woman.   Why did I tell her this?  Was it to give me an excuse if something happens in the future?  I do not think so but I want those junior, senior and professional psychologists to let me know why one does this.  My wife took it well – I talk to her about everything.  I always have.  What do you think?  Did I make a mistake?  Is honesty the best policy?