when you have ds..........

Oh, aren't you two going to be a pair?  Your fiance is right.  He is able to eat and drink at the same time without washing his food away like your RNY -- however, that being said, it may not be that comfortable to do at first, just because it may make him feel full very fast.  I usually drink at the end of my meal unless the food is dry and I'll drink a little during dinner.  Also, make sure he's eating full fats as a post op.  If he doesn't get enough fat, he could wind up constipated.