I think you see the initial outburst like you have stated. The MLCer is proud of themselves and their newfound "love". After all, they are on a quest to "change" the past and find that "happiness" that fills their world. High energy is extrovert activities and low energy is introverted. One is very active, runs through the money, physical affairs while the other is more emotionally detached, emotionally involved with the other person.
Cali, I think that you made a very astute and logical observation that despite low energy or high energy, the first phase is a distinct eruption. After the initial high, the high energy may leave the alienator and try to come home-hence the clinging boomerang as they go back and forth. The low energy may actually take longer because the emotional bonds and the ability to self-medicate the depression without full involvement creates a huge issue with withdrawal even though on the outside they appear to be the same lifeless and loveless creatures.
Even the vanisher makes a blip on the radar after the high begins to wear off. All try to avoid and hide and returning to the other person is much easier than to accept responsibility for their actions. However, they will all face their demons at some point and they will return. It is not a matter of will, but a matter of when.