I am 33 and had a total colectomy with my rectum removed like 2 months ago and I experienced something called retrograde ejaculation for about 3-5 weeks after the surgery. There was really no problem with function per say other that the baby batter was heading the wrong way. It should take a little time to sort itself out. Everything seems to be working as expected now. From a guy's point of view, go easy on him with it because if he feels anxious about it it may manifest itself into something even worse :). Hope everything works out. I am sure he will be fine.