We think that there are different brain systems for sex, romance and attachment. Indeed, sexual arousal is mediated by an area different from romance: the hypothalamus; and fMRI studies show activation in the hypothalamus is correlated with erection size in men. Sex and romance often happen together, but often they don't, too.
We had asked our study participants not to think about sex. The group results showed no effect in the hypothalamus, but a few individual subjects did show activation there. For some people, sex was impossible to separate from romance.NEXT