Hi, Thank you for sharing your concern with us through Practo. Feeling gross, sad, depressed, aversive after an orgasm is not uncommon. And we don't have any well-defined theories to explain it. Apart from several weird sounding theories, some scientists believe that it is the changes in the brain chemicals after orgasm, that make us react differently. Some psychologists believe that it's your past experiences in relationships (sexual or romantic) that get inscribed in your mind and may surface after sex and make you sad. Dr Dušan Potkonjak, associate specialist in psychiatry says this: “Human reaction is not segmental. we need to explore the whole history of [a patient’s] sexual encounters and their pattern of human relationships. Our potential for intimacy can be badly affected if our first experiences were humiliating or we experienced rejection – it’s like Pavlovian conditioning.” "Ultimately, then, the causes of post-coital sadness are elusive and invariably subjective. It can be a chemical problem for some and an existential one for others. Or it could simply be down to an unfortunate romantic incident in your past."