It is natural that you feel attracted to other females beside you wife. We are animals, although advanced ones. Our genetic codes urge us to preserve our genes.
I will not lie. I had felt an attraction to a few women over the years while i had been married this last 6 years. Technically as humans its impossible no to do so. But what make us different to other animals is the capacity to decide if we act or react upon that feeling. The opposite has occured too, i´d been in situations where a woman clearly flirts with me even though they knew i was married. I had clearly put a distance on those women using courtesy and coldness. I belive it is completelly an act of CHOICE.
There will allways be easy men and easy women. There will always be opportunities.
I recommend you to redirect that feelings to something positive. Like developing those fantazies with your wife, or some kind of manual labor, or studying.
Also you should put some distance with your friend.