It had been your wife's sister who first mentioned to you (two years ago) that the reason your wife had been feeling so unhappy was because she had a deep need for more romance and satisfying sex in her life. Of course, you were hurt and upset to hear that, but you also felt guilty that you were not providing her with what she needed -- but you were not sure what you could do to make the situation better. When you said that to your sister-in-law, she was the one who said that there was just one obvious solution -- that you should encourage your wife to start dating other men. You were quite taken aback by that idea at first, but your sister-in-law was persistent in arguing that, if you truly loved her, it was what you really needed to do -- and eventually you accepted that she was right.
Even so, you didn't think your wife would do it, so you were surprised that when you told her you thought that was what she should start doing, she agreed with you almost immediately, and asked you to help her set up a profile on a couple of online dating sites. Two weeks later she went on her first date, and she was soon going out at least once, but often two or three times every week.
At first, she dated quite a number of different men, but after about a year she started to "go steady" with just one man -- the man who was now her boyfriend. She now spends all of every weekend with him, and they also travel together, and she has told you many times how wonderful he is -- how he brings her flowers every week with love notes included -- and how incredible (and well-endowed) he is in bed.
It does warm your heart to see how happy she is now and you are happy to accept your role now as her devoted cuckold.