Being married for over 40 years results in numerous changes in thoughts, plans, and maybe even dreams. It also results in changes in your sex life. Not only do your sexual interests change but the more obvious acceptable sexual interests in society change as well. I'm not sure that what couples do in private really change but what they are willing to discuss with others does change.
When we were first married the idea of "wife swapping" was a new and exciting topic, not that it hadn't gone on in the past but now it became part of the public discussion. The term "Wife swapping" son became unacceptable because it implied that the wife was property that could be traded around at will. The term "Swinging" became the acceptable term followed by "Lifestyle".
The other change that occurred during this time is the Internet. The Internet probably has had a greater impact on people sex lives than it has on any other facet of life. Porn is responsible for a huge portion of the traffic on the Internet.
The Internet and the ability to share stories (fact and fiction) has probably had the biggest influence on Amanda's and my sex life. Things like swinging, voyeurs, exhibitionists, etc. were concepts that neither one of us even knew existed and we didn't find out until we had been married for at least 25 years.
Years ago I came across a series of stories by "The Warthog". I can't recall the name of the site where I found them (after several years the site transferred it's content to Literotica) and I was hooked. A whole new world opened up to me and eventually Amanda as well.
This is where I discovered that the idea of Amanda having sex with another man turned me on. It didn't matter if I was watching or if I heard about it after the fact I knew this was the direction I wanted to go.
My initial way of addressing this was to convince Amanda that she could be the target of men's sexual interest.
Amanda grew up in a conservative catholic household. Sex was not discussed and there was an implication that it was not something to be explored. As a teenager Amanda was well developed. She probably had the biggest boobs in the school, including the teachers. I must admit that before I even met her I knew who she was based on the comments of the guys around me. She felt her big boobs were a curse, she hated them.