People in the early stages of love have smaller grey matter in a region of the brain involved in reward.
It’s possible that the brain adjusts to the intensity of feeling. But how fast?
But we have to also consider that the scans were taken at just one point in time. So we don’t know if being in love shrinks the right-dorsal striatum. Maybe people with less grey matter in this area are more likely to fall in love.
Kawamichi Hiroaki, Sugawara Sho K.; “Being in a Romantic Relationship Is Associated with Reduced Gray Matter Density in Striatum and Increased Subjective Happiness”; Frontiers in Psychology vol.7, 1763 page, 2016 year