There's my wife, me, and this other couple same age. Despite being friends for a long time, having traveled together, dinners, etc, only a year ago (Spring 2018) we started going to the local beaches together. Since day one at the beach, topless became the norm. It was a nice surprise, since my buddy's girl is very sexy and has nice breasts. You can read the details here:
https://forum.oneclickchicks.com/sho...7&postcount=23
Since then, we've hit the beaches more times than I can remember and topless is still the norm every single time. Even this one time another girl friend came along, keeping her top at first and then joining the other girls showing us her glorious big round breasts, which I had imagined for such a long time. Good times.
Trust and confidence has kept rising between the four of us, and it has become so natural to be half naked in the beach, my wife with a tiny brazilian thong, his wife in an over-sized bikini bottom that hints her bits, just chillin or playing or fooling around. Changing clothes at the beach has also been adopted, and a few times the girls have gone comando after the beach for lunch or drinks. I think by now we all have seen each other flash something more than just breasts.
It has become a really nice and fun friendship. I wonder if it'll go any further.