"I'm want to make sure my wife doesn't do anything stupid." Vegeta replies rather flatly. Bulma was always so excited over new stops and a chance to explore, but she also had a habit of getting in over her head at the worst possible times. With how much room it sounded like they were going to have to cover, Vegeta's not sure it's the best idea for him to be too far away as she went poking around, let alone on separate islands.