Several physical and emotional factors can contribute to depression after intercourse. Post-coital depression can be caused by a number of things and some of them include;

Hormones

According to Healthline, depression after intercourse can be related to hormones that are involved in love and attachment. During the process, your hormonal, physiological, and emotional processes are at extremely high. You’re feeling an unbelievable level of impulse, physical and otherwise. Then, suddenly, it all stops and your body and mind need to return to baseline. It is this physiological ‘drop’ that can bring about a subjective sense of dysphoria.

Poor self-image

If one partner has a poor self-image after intercourse, they may become depressed. This can be due to feeling like they’re not attractive or sexy, or that they’re not good in bed.

Negative memories

If one partner has negative memories of previous intercourse experiences, they may become depressed after intercourse. This can be due to feeling like they’re not in control, or that their partner is too demanding.

Feeling guilty

If one partner feels guilty or ashamed after intercourse, they may become depressed. This can be due to feeling like they’ve done something wrong, or that their partner is not satisfied.