Question about film "The Heartbreak Kid"

In Neil Simon’s The Heartbreak Kid, a classic movie of the 70s, the protagonist is a charming sociopath who divorces his newly-wed wife, on their honeymoon, to go chasing after a woman, Kelly (Cybil Shepherd) he just met. When Lenny (Charles Grodin) admits to the woman’s parents that he has just split up with his wife of only three days, and intends to woo their daughter, the father (Eddie Albert) is furious and he tells Lenny to get the hell away from his family. Undeterred, Lenny actually follows them to Minnesota (crazy behavior) where he shows up at their doorstep, confronting the father again - who tells him, again, to get the hell away from his family and never come back. Finally, after eloping with the blonde dreamgirl, she manages to convince her parents to have Lenny over for dinner.

At dinner, Lenny gives a dramatic, pompous speech about how much he loves the “simple, honest” food at the dinner, and how he wants to get back to the land, and how “we’ve taken enough out of this country, and it’s time to give something back,” etc etc. The mother completely falls for it, apparently, but the father only pretends to be impressed. After dinner, Lenny goes into the father’s office for a private meeting, wherein Mr. Corcoran tells him he’s a fraud and a hack and a bastard, and that he will NEVER let him marry his daughter. He even offers him five thousand dollars to get away from his family - when Lenny refuses, Mr. Corcoran raises it to ten thousand. He keeps raising the offer, eventually to fifty thousand dollars (!!!) - but Lenny says, “I didn’t come here to negotiate for your daughter - I came here to fight for her.” Mr. Corcoran responds: “Have you ever met a brick wall? Well, you are talking to a brick wall!”

The next scene is Lenny and Kelly getting married.

How the hell did this happen?

Are we to assume that Mr. Corcoran finally caved in to Lenny’s demands, even though it is not actually shown?

Are we to assume that Kelly’s mother, who clearly liked Lenny and fell for his con-artist shtick, convinced her husband to allow Lenny to marry Kelly?

WHY on God’s earth did Mr. Corcoran, after flatly refusing to allow the marriage, so quickly change his mind?

Does anyone who has read the book that this is based on have any further insight into this puzzling quandary?

Well, if she’s of age, is there really anything he could’ve done to prevent the marriage?

I thought the point of the marriage scene was to show that he’d gone full circle. Marrying Kelly wasn’t a happy ending for him, just a short stop before his next infatuation.

IMO the next scene of the marriage was meant to make us laugh that “the brick wall” didn’t quite stand up to the overwhelming assault upon it. Skipped over any arguing between the mom, dad, and daughter - he was going to marry the daughter and that’s that. What don’t you get? It was the end of the movie and he was NOT going to take “no”, in his obsessive self-centered way. It was a done deal, why drag the story out?

Besides, I think the girl was old enough to marry him without daddy’s permission, wanted to marry him, and rather than risk being estranged from their beloved lil princess, or have her elope (!) - dad just caved and sprung for a fancy wedding. It’s going to fail, of course, but what else can dad do?

I don’t see how Lenny is a con artist. He married Lila because he loved her (or, at least, thought he did), and got some serious buyer remorse on the trip down to Miami. And until the Key Lime Pie scene, the audience is on her side – Lila is no winner and the idea of “forty or fifty years” with her is appalling. That’s why he’s so taken with Kelly. It isn’t until after he decides to leave Lila that we see any reason why he shouldn’t be doing it (I love the way May makes the audience complicit in Lenny’s actions, and then shows us what a bastard he’s being).

Lenny is sincere about Kelly, but the ending implies he will tire of her, too, and that he really doesn’t know what he wants.

Yes plus a bit more unease. It is pretty obvious that Kelly isn’t all that interested in Lenny really. She is bored having sex with him though he thinks it’s fantastic. At their wedding the same song is played as at the wedding at the start of the movie, “Close To You”, and the final shot shows him sitting alone.

In classic fiction the hero’s troubles are meant to allow him to learn something about himself. Lenny learns nothing - he just thinks he needs the “right” wife as a substitute for personal change.

Wasn’t it pecan pie? I offered my wife many chanced to have it on our honeymoon.

Yes, it was definitely pecan.