A young and independent woman struggles to determine if she has made the right choice in marrying her husband when her irresistible and impulsive ex-boyfriend tries to win her back while she is on her honeymoon.

Like the logline. Makes me wonder does she have pro and con lists, how similar and different are the husband and ex-boyfriend, did she marry the husband because of what other people think?

The story has a lot of potential for comedy -- it is a comedy, isn't it? -- because it takes one step further the premise of "My Best Friend's Wedding". In that movie, the Julia Roberts character attempts to break up her best friend's marriage before he says "I do." In this logline, the guy tries to after the marriage is a done deal.

While the woman is cast as the MC in this logline, frankly, the guy trying to break up her marriage and win her back seems more interesting. He -- not her -- seems to be driving the plot, the one who has to do the hard work of story, will have the better scenes. Consider again, "My Best Friend's Wedding": the female best friend trying to stop the wedding is the protagonist, the one who drives the story, not the best male friend.

So I suggest either make the guy the MC -- or switch roles. That is, make HER the one who invades HIS honeymoon, determined to win him back even though he has already said "I do" to her competition.

Something like: A head-strong woman invades her ex-boyfriend's honeymoon to win him back.

As far as the working title, "The Newlyweds" seems rather prosaic. It's tempting to suggest "My Best Friend's Honeymoon", but that may be too obvious a call back to the other movie. (Although it is safe to assume that a script reader, producer, or director, will associate the two.) Maybe something like: "I Do -- I Don't" -- the diametrically opposed positions of the couple in conflict.

fwiw.

Good points raised above.

Also are "...young and independent..." relevant to the story? If not then better to change them to a shorter description that aids the reader in understanding the type of character and conflict she will encounter.

Also "...woman..." is too generic a description in this case; what kind of woman? I find the character's job a good way to hint at her place in society, out look on life, aspirations, etc...
For example if you define her as either a; lawyer, environmental activist or sculptor. You strait away tell the reader what kind of person she is.

Lastly I would re structure the logline for the next draft. Put the appearance of the ex-boyfriend in the beginning of the logline, then after that what she does.
The reason is that as the reader reads the logline they develop the story in their mind in the same way it would be told in the script/film. Therefore to help this happen the order of the events and actions in the logline would need to follow the same order as the finished story.

Hope this helps.