Wearing her lover's tee shirt may be a subconscious love reinforcement for her companion. Odor can have an positive role in our everyday life. We know animals are attracted to each other by scent. Many animals can tell their young apart by scent. Animals mark territories by their spray or pheromone.
Insects signal they are ready to mate by emitting phermones.
Even modern science now uses phermones to catch certain insect pests. New mothers will often remark that they love the smell of their babies. Better yet, human phermones are now available to you on this web site. Pheromone are detected by an organ which is three inches inside the nose with nerve connections to the brain. In modern times natural pheromone are not as dominant because of personal hygiene and the masking of the scent caused by using deodorants.