And the disappointment is heightened by the potential that the film had leading up to the map theft, even though it was still salvageable until we learn David is married.
A better fulcrum for Jenny's revelation could have been made through her experience with Helen (the ditz) and tandem with Danny betraying David by discouraging Jenny's decision to marry.
I thought this was where the film was going.
So what could have been a great film with the premise of "that which is not earned is not valued" instead became "men are invariably slime balls; don't trust them."
IE - if David had not been a fraud, there is no reason to believe that Jenny would have changed her mind at all and all of her reasons for making the choices she did would have been justified.