Both the main islands of Vanua Levu and Viti Levu are staggeringly beautiful with a rich Melanesian culture as well as the influx of Indian culture which in the past has led to political tensions. Because of its proximity to Australia and NZ, there are many resort options on these two large islands, though perhaps nothing in the serious luxury class which really only exists on the surrounding private islands. With only three days I'd forget about these island resorts and just rent a car and drive around. Suva has the newly renovated Grand Pacific Hotel where Prince Harry and Meghan stayed recently.
Personally I'd feel a bit self-conscious as a solo visitor to the island honeymoon ghettos.