Although this might primarily have to do with one or the other partners in a couple (e.g. erectile dysfunction in men, vaginismus in women), oftentimes, sexual dysfunction is a couple’s problem and must be addressed by assessing both partners.
This is the diagnosis given when all the other tests are normal. Many couples failing to conceive after 1-2 years of trying, with all the usual tests coming up normal, may actually have age-related sub-fertility or endometriosis. On the other hand, there may be other diagnoses or medical problems that we have just not come to understand yet. The most recent diagnosis of “Decreased Ovarian Reserve” was only elucidated about 20 years ago.