This is based on something that really happened. Early in our marriage I started having cuckold fantasies and told my wife about them. At that time we were living in an apartment and there was a guy in our complex that invited us to a small Super Bowl party at his place. My wife had been telling me that he flirted with her regularly and she had also admitted she thought he was sexy. We had joked about her having an affair with him, but nothing had happened. When he invited us to his party I suggested my wife go without me while I stayed home with the kids. Thus ensued a conversation like the captioned photo. I told my wife that it was only fair that I stay home with the kids since she had them every day while I was at work, but I also admitted that the idea that something might happened between her and him turned me on a lot. She went to the party and he hit on her as expected, but nothing sexual ever happened between them. However, we talked and role played about her having sex with him during foreplay many many times.
When he moved, there was a part of you that hoped it might mean that she would stop dating him and might even stop cuckolding you -- and perhaps might even agree to start having sex with you again every once in a while -- but that's not how things have worked out, so you continue to try to show her how much you love her by being as good a cuckold for her as possible.