If you are flying to Croatia, the closest airport is Rijeka(only a small airport) and then Zagreb. It takes ~1 hour drive from Rijeka and ~1.5 hour from Zagreb to the wedding venue. Another option is to fly to Venice in Italy. The wedding venue is ~3.5 hours away from the airport in Venice. You can find driving directions here.
If you want to stay next to the sea you can stay somewhere in Rijeka.