During breeding season, I wait 5 days after separation for feeding to return the male to the females cage. Haven't had any problems and they seem to have digested enough to resume mating.
Quite simply, ETB's don't like to be held. All of our perches are removable in order to avoid stress when removing them from the enclosure. Trying to pry an emerald from a permanent perch when they don't want to let go can be very stressful to the snake and keeper as well as possibly being painful to the keeper. It is quite easy to get them to move from the perch to the exercise "tree" and most will tolerate being hand carried back to the cage. However, if you insist on holding them, never restrain them or make sudden moves as you will likely be introduced first hand to their business end. LOL
CraigC