Two or three times a year, you and your wife and her sister and her sister's husband go away on vacations together. Your wife and her sister always have a LOT of sex on these vacations -- always involving cuckolding the two of you. It was really awkward for you and him the first few times, but you're basically used to it now, and you even sometimes talk about it with him -- about how you both took a while to learn to deal with it emotionally and how you now have gotten to the point where you really hope that the two of them are having a good time.
Our cuckold journey was a very slow process. I encouraged her to cuckold me for many years before anything ever happened. In the early stages it was just fantasy talk, for example during foreplay we we would talk about her being with other men which would get us both turned on. At first my wife was reluctant to do anything at in real life, but eventually, she felt comfortable dancing, talking and flirting with other men. Eventually this did result in her kissing with a guy one night which she told me about after we got home. This really got us both super turned on. She has told me that kissing another man was probably a big turning point in her decision to ultimately cuckold me.