Low desire is the most common sexual concern there is, and it’s the one most likely to be treated as psychological when it isn’t. The order below is deliberate.
Rule out first
Medication. The largest single cause and the most reversible. SSRIs and SNRIs are the main offenders and the effect is substantial and well documented. Also: some blood pressure medications, hormonal contraceptives for some people, finasteride, antipsychotics, and opioids.
If desire dropped after starting something, that’s your first conversation. More here — and don’t stop a prescription on your own.
Hormones. Thyroid dysfunction. Low testosterone, in any sex. Prolactin. Perimenopause and menopause, which is enormously under-recognised and frequently arrives a decade before people expect it.
Sleep. Chronic sleep deprivation suppresses desire reliably, and untreated sleep apnoea is a common and missed cause.
Depression, and chronic illness or pain, either of which is sufficient on its own.
Alcohol. Regular drinking lowers desire over time even where a single drink appears to help.
Then the model
Before concluding there’s a problem, establish which kind of desire you have. Responsive desire — arriving after arousal begins rather than before — is entirely normal and gets misread as absence in a very large number of people.
If you never think about sex spontaneously but enjoy it once you’re in it, that isn’t low desire in the clinical sense. That’s responsive desire being measured against a spontaneous standard.
Then the brakes
Desire runs on an accelerator and brakes, and low desire is more often heavy braking than a weak accelerator.
Common brakes, and none of them are trivial: exhaustion. Resentment, which is the most powerful and the least discussed. The mental load, and the specific unsexiness of being the person who runs the household. Body self-consciousness. Fear of interruption. Not feeling desired as opposed to being wanted for sex. And the accumulated pressure of being the one who has to decline.
The desire map sorts accelerator from brakes, which is usually more useful than any general advice.
Then the specifics
Is it global or situational? No desire for anyone, ever, including alone — versus no desire for this partner. Different problems, and the distinction is the single most informative question a clinician will ask.
Did it change, and when? A gradual decline over a decade and a sudden drop three months ago point in different directions.
Is anything else going on in the relationship? Desire is frequently the first thing to go when something else is wrong and unspoken.
On asexuality
Worth stating. Some people simply experience little or no sexual attraction, and that’s an orientation rather than a dysfunction. It doesn’t need treating, and a clinician who assumes it does is doing something inappropriate.
The distinguishing feature is distress and change: an absence that has always been present and isn’t troubling you isn’t a symptom.
Where to take it
A doctor first if anything on the rule-out list applies. Then, if it’s relational, couples or sex therapy. A coach is reasonable for the context-and-brakes work and is not the right route if there’s pain, a medical cause, or depression underneath.