Can an enlarged prostate decrease a man's libido?

My husband and I are 31 years old and we haven't had for over a year. Other than that my husband is very loving and caring and I can say with absolute certainty that he is not having an affair. He just doesn't want to have ,says he doesn't enjoy it, and these days if he tries to, he fails to have a strong . He wasn't like this when we were going out and I dont look much different than I used to. He has been given different tests by a specialized doctor, Blood CP, Testosterone, Random Plasma Glucose, S. Urea, S. Creatinine, USG Whole abdomen, ECG, and Semen ysis. There was another test where it tested if the blood flow in his was normal. All tests came out normal except for a little fat around his lever and expanded prostate. He tried the semen test couple of times but failed. My husband has also earlier been to a psychiatrist who had prescribed him medicines like viagraj, stelong, herbal V, even anti-depressants, meds to help him relax, but nothing helped. is a need right? How is he living without of any kind for so long? How is he satisfying himself? He does have ejaculation from time to time, not very often though. I have spoken to other men and they say they can tell he is not gay. He is not into s either. He doesn't seem attracted to other women or men. We tried going on long vacations and got drunk, even that did not motivate him. And he doesn't want me to leave him either. He gets upset if I talk of having an affair. What is his problem?I am clueless.