After dropping his wedding band in a wishing well, a dissatisfied middle-aged husband discovers he can experience life if he hadn’t got married simply by removing his wedding ring, but must choose which life to lead when his ring’s power begins to fade.
CHARACTER: a dissatisfied middle-aged husband will do, I think. Dissatisfied, because he must flirt with the other side, and middle-aged, because he must be married long enough to justify the aforementioned flirting.
EVENT: The wedding ring gets enchanted (I don’t care much about how it happens—wishing well or not) and the protagonist realises that he has the power to live two lives; married and single, by wearing and removing it, respectively. Great! An Out of the Bottle type of story with potential for character growth.
ACTION: To choose… Hmm. It has been said often in this forum: choice is a momentary action, not one that can drive a movie.
Moreover, “choose which life to lead”leaves us in the dark, as far as the plot is concerned. It is too generic.
Why not come up with a specific goal, instead?
Since this kind of story is about appreciation of what one has (once the magic fades away, the protagonist is back at his previous life, but wiser), the story has to be about his relationship with his wife (and kids, if any—I would recommend yes). Rediscovering something that has been lost. It has to be about appreciating his family.
And the parallel new universe serves as an opportunity (through some external goal) to get to this appreciation.
For example, in the “single” universe, his wife is obviously not his wife, but the wife of his boss. Or her boss. The boss appears in both universes.
(I can’t seem to get that episode of Family Guy out of my head, where Peter lives a parallel universe where Lois is married to Quagmire.)
One final note: is a wedding band not the same as a wedding ring? I suggest you use only one term, to avoid confusion.
You have a strong hook but not a strong inciting incident.
You need a specific scene at the beginning of the story that establishes the problems in his marriage.
Then introduce the hook about the Wishing well.
So nice hook, but you need to establish the problem in a more compelling way.