There are so many brilliant, funny, wildly talented people in and behind this movie that it is difficult to understand why it is so hard to watch.

Writer/director Nick Stoller is responsible for comedy hits like “Get Him to the Greek,” “The Muppets” (2001), and “Yes Man” along with lesser entries like “Zoolander 2” and “Night School.” He filled the movie with top comedy powerhouses Will Ferrell and Reese Witherspoon, supported by immensely talented up-and-coming performers Geraldine Viswanathan (“The Broken Hearts Gallery,” “Blockers”), Meredith Hagner (“Bad Monkey”), Jimmy Tatro (“Theater Camp,” the under-appreciated television series “Home Economics”), and solid supporting comic actors Fortune Feimster, Jack McBrayer, and Rory Scovel, plus the very funny stand-up comic Leanne Morgan and Keyla Monterroso Mejia, a standout in this month’s “One of Them Days.”

But one crucial ingredient is missing: the stakes. The entire premise for the film is that a luxury island destination off the coast of Georgia has been double booked. Why? Because the elderly lady who took one of the reservations had a heart attack and died before she could write it down with a working pen in the hotel’s calendar book. Fun, right? It is close to impossible to care which bride gets what services and even more difficult to care about any of the people who do care about it.

There is single dad Jim (Ferrell), whose entire life has revolved around his daughter, Jenni (Viswanathan) since her mother died when she was a little girl. It is supposed to be both funny and endearing that she is his whole world. It is not. For example, the two of them have a “cute” little musical number they like to perform together, apparently without ever having listened to the lyrics. It’s “Islands in the Stream,” which is of course a love song duet with the couple singing about making love.” Ew. Jenni wanted her best friend and maid of honor Heather (Mejia) to make all the plans, so Jim has not confirmed any of the details.

In the other corner is reality television producer Margot (Witherspoon), who does not get along with anyone in her family except for her baby sister Neve (Hagner), who is her favorite person in the world. As a producer and, if this is not redundant, control freak, Margot has made three visits to the island to nail down everything up to and including the canapés. And as someone who feels her family does not appreciate or approve of her, she is ready for battle over every one of those details.

Both have emotional attachments to the venue. Jim and his late wife were married there. Margo and Neve spent summers on the island with their late grandmother. At first they try to get along but very soon this leads to a succession of petty, silly, and mostly dull efforts to obliterate each other, with escalating hijinks that make these people more and more unpleasant. A bride gets hit in the face, leaving a huge bruise. A wedding party gets knocked into the water. There is a sharp contrast between the slapstick and the exquisite music (not “Islands in the Stream” — the soundtrack also features a gorgeous song from Sondheim’s “A Little Night Music” and operatic selections). It is a nagging reminder of the gulf between the meaning of the events, which even the couples seem to have overlooked, and the ridiculous pettiness of the conflicts.

Parents should know that this movie has a lot of very strong and crude language with sexual references. There is also a lot of comic peril and violence. No one is badly hurt but we do see some bloody woulds and a bad bruise.

Family discussion: Would you want to attend either of these weddings? What weddings have you been to that you especially enjoyed?

If you like this, try: better movies with the cast including “The Broken Hearts Gallery,” “Stranger than Fiction,” and “Legally Blonde”