Soon after Emma Ganzarain moved into her boyfriend’s apartment in Oslo, the couple got to work on a redesign. They added light-colored herringbone floors, with radiant heating to combat the Norwegian chill, and taupe kitchen cabinets. In the living room, the pair swapped out a purple light fixture for a white one and replaced a maroon armchair with a chair of a similar size in off-white. When the work was just about done, Ms. Ganzarain, 26, posted some before and after photos on TikTok. “All men need a woman in their life,” she wrote in the caption. The reaction was…