Does phillip and syrena live happily ever after at the end of On Stanger Tides?

At the end of "On Stranger Tides," Phillip and Syrena do not have a conventional happy ending. While they express their love for each other, Syrena ultimately chooses to return to the sea, leaving Phillip behind. Their relationship is marked by sacrifice and longing, suggesting that while they care deeply for one another, their happiness is complicated by their differing worlds.