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 from your current location to the wedding venue here.
If you want to stay next to the sea you can stay somewhere in Rijeka.