Welcome to e health forum.
Sexual problems range from weak erections, premature ejaculation, lack of ejaculation , lack of interest and so on.
It is very hard to evaluate your husband's condition without a complete medical history and physical examination findings.
There are a lot of causes that can affect male sexual performance including conditions causing damage to nerves, arteries, smooth muscles, and fibrous tissues ; Lifestyle diseases like hypertension, diabetes, Smoking, being overweight and avoiding exercise are possible causes of Erectile Dysfunction.
Your husband should consult with a urologist or a sexologist, for a proper counseling and examination.
A proper diagnosis will help in providing proper therapy. He can ask his doctors a prescription of medications like Viagra or Cialis, which may help him improve his sexual performance.
I hope this helps.