What happens in the brain during an orgasm? One word: oxytocin. Sexual intercourse promotes feelings of attachment over time in large part thanks to oxytocin, which is produced in the ventral tegmental area of the brain.
This chemical could aptly be nicknamed the "glue chemical" since it does such a swell job of binding people together. As oxytocin levels crest, it calms and combats the early phase intensity of romantic attachment, easing us into more stable relationships. Research confirms that in women especially, oxytocin fosters trust, happiness and bonding. To that end, this also is the same nonapeptide compound that bathes a new mother's brain, establishing the maternal link between her and child, and what spikes when we look at a picture of a loved one [source: Marazziti].