My husband has a orgasm but no fluid came out this has happen a few times hes 30yr. What can cause this?

Retrograde? Some men, especially on some of the stronger medicines ("mellaril" / thioridazine was most famous) will ejaculate backwards into the bladder. It is not dangerous, but if it is troublesome, a urologist can offer help. Most men occasionally have the sensation of an orgasm but without ejaculation, and this is usually self-limiting and a non-problem.
Medication? Some medications can cause retrograde ejaculation, which would result in little or no semen emission. The semen goes back into the bladder and is urinated out later. Also, some neurologic conditions may cause this as well. I would talk to his doctor about checking this further.