Complex sentence: Jerry and George are at the U.S. Open where George mentions that he had invited his girlfriend Gwen to a party, to which Jerry replies by saying is a bad idea, as he cannot socialize with others when he is with his girlfriend.
Split into simpler sentences: Jerry and George are at the U.S. Open where George mentions that he had invited his girlfriend Gwen to a party. Jerry says this is a bad idea, as he cannot socialize with others when he is with his girlfriend.