THE MISTERLESS ISLAND by Julie Verna

Or what if, as the stranded group of men realize they're being feminized ("My God, this is like one of those stories-") and they wonder if they'll be able to escape the clutches of these evil androphobic feminizers...

Then they're called to see the leader. Food and drinks are available but most of them refuse, figuring that it's laced to with feminizing drugs. Her friendliness makes them even warier...

But then she says, "By now you've noticed that your bodies are changing. You are becoming women. This is not anything we're doing but a magical property of this island that even we don't really understand (although it probably has something to do with that pink steam coming out of the volcano there...), but at this point it is still reversible. All you have to do is leave this tropical paradise and within a few weeks or months you will be back to the way you were. And if you don't want the changes to continue to the point where they're irreversible then you should go. Forget that raft you were secretly building we will give you one of our best lanteen boats. We're not in the habit of holding people captive or changing people against their will. If we did that we would be no better than the cruelly patriarchal society we fled all those years ago. If any of you chose to stay, then Welcome, Sisters. You will be given all the rights of citizenship and you'll be a part of something magical; a society that while not without conflict will nurture you and help you unlock the goddess within-"

...Or some such utopian mumbo jumbo. Another property of the island is they live a long time, so they only need the occasional new gg citizen or voluntary transformee to maintain a stable population level. The drama is pretty low key, the one, most paranoid of the male travelers finds out that his oldest and best friend on earth wants to stay. For him/her it's an answer to her prayers. This freaks the frightened guy out, he thinks his buddy has been brainwashed, but then the friend gives him plenty of examples of why she was trans all along. They part as friends; And five of the six castaways return to civilization....

This plot subverts the whole fiendish femdom theme, which is fine if you like that sort of thing
but it's just not what I like to read.
~hugs, Veronica