I asked because some antidepressants can cause the problem you describe.
It is, sadly, fairly common with men who have had prostate surgery. If it continues you should talk to your doctor about
it. You could ask him/her about
this study that found the drug Cabergoline quite helpful for men in your situation.
www.everydayhealth.com/sexual-health/0524/drug-restores-normal-orgasm-in-men.aspx