We sort of got into cuckolding by accident though it was really inevitable. I'd swung with my first wife (who sadly died when she was only 40). When I met Lynn she was fucking around behind her husbands back but we hit it off and became a couple even though she was still with her husband. She was very interested in my swinging past and didn't need any persuading to give it a go and we did that for many years (and still occasionally do). But she still continued to see other men too. To be honest, though I had a lot of fun swinging and having sex with other couples, the thing that really turned me on was seeing my first wife and then Lynn getting fucked by other men.
When I asked Lynn to marry me she was quite hesitant about moving from one marriage (which hadn't been very happy) to getting tied down to another man. But when I assured her that it didn't mean she had to stop seeing other men, she agreed.
Over time, the swinging we did became less and me watching or hearing about Lynn fucking other men became much more the norm.
We will have been married 21 years this year and Lynn is still fucking other men, we are still very much in love and couldn't be happier.
So as I say, given how our relationship started, it was really inevitable how things worked out. Not really planned as such but it has been the ideal fit for us both.