A Styrax? Yes, it could be... the flowers were fragrant, you said. The leaves are correct, I think. The other thing I thought it looked like was a Halesia, but I didn't think a Halesia would have found its way to a greek island, though you never know! Similar flower type, though, even if from the wrong part of the world, but Styrax officionalis comes from the right place, around the mediterranean, so that is a sensible choice!