"To release the chemicals" means to cause or allow certain substances called chemicals to be set free or made accessible in a specific situation or environment. Full definition
It makes your body release a chemical called oxytocin that can help lower your stress, bond you to your partner, and help you get to sleep faster. (webmd.com)
Brain neurons naturally release this chemical in a wide range of situations. (sciencenewsforstudents.org)
Your body releases chemicals which make us feel more attached and more in touch with our loved ones. (luxematchmaking.com)