Too Much Overlap
Simply put, when there is too much overlap while posing couples, it looks like one subject is hiding behind the other. If you are more into percentages, you generally do not want to overlap more than 20% of the body. There are, of course, exceptions to this rule, as there are exceptions to many of the rules in photography. The exception here occurs in photojournalistic moments when the expression sells the image, or the height or other factors allow enough of the “hidden” subject to be revealed. You can also turn the couple to balance out the subjects.