Strong paint smell after painting after 6 weeks

Hello! It was similar for us in 2020. I ventilated a lot and in between placed an electric diffuser with the windows closed. Only one drop of real natural rose oil was added to the water. It improved enough for someone to be able to sleep in that room again, but the smell was really gone only in spring when the windows could be left open for weeks for cross-ventilation. Tilting the windows was not enough.