It sounds like The Heartbreak Kid.
A 1972 film with Charles Grodin as a guy who gets married, realizes the error when his character falls for blonde haired non-Jew, played by Cybill Shepherd.
All in all they were terrific in this Elaine May directed film, based on the Neil Simon comedy play Change of Plans.
There was a less enjoyable update in 2007 from the Farrelly brothers and featuring a number of supposedly funny actors. Even Jerry Stiller, Polly Holiday and Rob Corddry could not rescue it.